ap star Jay-Z joined Rihanna on stage for two songs as she launched her new album, Rated R, in Brixton, London.

The Barbadian singer, 21, was playing her first show since she was assaulted by her ex-boyfriend, Chris Brown, in February this year.

She emerged on stage in an eye mask and studded leotard to perform a selection of new songs and hits like Take A Bow.

Jay-Z made his surprise appearance for the finale, performing his recent hit, Run This Town, and Rihanna’s Umbrella.

Several members of the audience, made up of competition winners, held aloft umbrellas during the song in an unorthodox moment of crowd participation.

The 45-minute show kicked off with two songs from Rihanna’s new album - Wait Your Turn and Russian Roulette.

Rihanna’s new album will be released on 23 November

Slow-burning and dramatic, they set the tone for a concert where many of the star’s hits were reinvented with distorted guitars and dark, pulsing synths.

The set-list included fan favourites such as Don’t Stop The Music and Disturbia, while Rihanna was also joined by rapper Young Jeezy for Hard, a track which is set to be the second single from her new album.

Jay-Z, who signed the singer to Def Jam records, had previously appeared at his wife Beyonce’s concert at the O2 on Sunday night, alongside Kanye West.

Star guests at Rihanna’s show included Adele, Keisha Buchanan, Tinchy Stryder, Emma Bunton and Chipmunk.

The presidents of China and the US have agreed to work together to tackle some of the world’s most pressing problems.

On climate change, Barack Obama said both sides agreed on the need for a comprehensive global deal in Copenhagen next month, not a political statement.

Mr Obama and Hu Jintao also agreed to push for North Korea to re-enter stalled talks on its nuclear programme.

But underlying tensions were referred to, with Hu Jintao calling for joint opposition to trade protectionism.

The two leaders held two hours of talks in Beijing’s Great Hall of the People, on the edge of Tiananmen Square.

Both leaders then held a joint media event at which they read out statements, but took no questions from listening journalists.

Mr Obama came to China for his first visit as president emphasising that China was now a major player on the world stage - and he turned to that point again in Beijing.

“The major challenges of the 21st Century from climate change to nuclear proliferation to economic recovery are challenges that touch both our nations, and challenges that neither of our nations can solve by acting alone,” he said.

With world leaders meeting in Copenhagen next month to discuss how to tackle global warming, climate change is perhaps the most pressing issue to resolve.

Mr Obama appeared to raise hopes that a deal could be struck in Copenhagen.

“Our aim there is not a partial accord or a political declaration, but rather an accord that covers all of the issues in the negotiations and one that has immediate operational effect,” said Mr Obama.

The comment seemed to be at odds with a much less ambitious statement from world leaders, including Mr Obama and Mr Hu, on Saturday at the Asia-Pacific Economic Co-operation (Apec) forum.

Tibet tension

Standing next to President Hu, Mr Obama also took up a theme that has previously proved contentious between the two countries.

He said China should resume talks with representatives of Tibet’s exiled leader the Dalai Lama to resolve differences over the Himalayan region.

China says the Dalai Lama is trying to split Tibet from the rest of the country and last year said previous talks had achieved nothing.

President Hu said China and the US would hold talks about human rights and religious freedom.

But, in an indication of China’s rising power and influence, he said the two counties should now treat each other as equals.

“We will continue to act in a spirit of equality, mutual respect and non-interference in each other’s internal affairs,” said Mr Hu, who spoke first at the media event.

He added that “trade friction”, which has recently increased between China and the United States, should be resolved on an “equal footing”.

“I stressed to President Obama that under the current circumstances our two countries need to oppose all kinds of trade protectionism even more strongly,” he said.

Later in the day, Mr Obama is due to meet the chairman of the parliament, Wu Bangguo, and there will be a state banquet in the Great Hall.

The US leader, who is not being accompanied by his family on the tour of China, is also fitting in visits to the Forbidden City and the Great Wall of China.

Mr Obama earlier visited Japan and Singapore on what is his first visit to Asia as US president. He is scheduled to fly to South Korea after leaving China on Wednesday.

Iran has played down a report by the UN’s nuclear watchdog that found questions remained unanswered about a nuclear facility near the city of Qom.

The International Atomic Energy Agency says Iran must explain the history and purpose of the recently declared site.

But chief Iranian nuclear negotiator Ali Asghar Soltaniyeh said the report was “repetitive” and Tehran had handed over all information on the facility.

Iran denies claims by some Western nations it is developing nuclear arms.

A UN team was allowed access to inspect the Qom site last month.

In its report, the IAEA said the delayed declaration of the plant raised concerns about other possible secret sites.

‘Full co-operation’

Mr Soltaniyeh told al-Alam TV: “Iran has provided all information about the new facility and the material inside it.

“We will later proceed with installing the required equipment. The facility will go online in 2011.

He said he was “comfortable” with the report, as it confirmed Iran was “fully co-operating” and that the activities at Qom were “in accordance with the IAEA instructions and limitations”.

“Inspectors scoured the facility for two complete days. Everything was compatible with the non-proliferation treaty,” he said.

Iran revealed the existence of the Fordo enrichment facility, which is being built about 30km (20 miles) north of Qom, in September.

The IAEA report said this did “not contribute to the building of confidence” and “gives rise to questions about whether there were any other nuclear facilities not declared to the agency”.

Iran’s delay in notification was “inconsistent with its obligations”, the report said.

The IAEA said it expected the Qom site to start enriching uranium in 2011.

“Iran’s explanation about the purpose of the facility and the chronology of its design and construction requires further clarification,” it said.

BBC Iran correspondent Jon Leyne says the report raises key questions about the timing of the site’s construction.

He says Iran’s declaration that it began the project in 2007 does not square with the IAEA’s evidence that there was work there as far back as 2002.

The report said satellite imagery showed there was work in Qom between 2002 and 2004, and that this had resumed in 2006 and “continued to date”.

But the US state department said Iran was still refusing to comply fully with its international nuclear obligations.

The report came after Russia said a nuclear power station it had been building at Bushehr in southern Iran would not be completed by the end of this year as planned because of “technical reasons”.

The BBC’s Richard Galpin in Moscow says the decision to delay the completion is an expression of Russia’s frustration at Iran’s failure to accept an offer now on the table from the international community.

Under a plan brokered by the IAEA and agreed by Russia, the US and France, Iran would send about 1,200kg (2,600lb), or 70%, of its low-enriched uranium, to Russia by the year’s end for processing.

Iran has raised “technical and economic considerations” with the IAEA and has missed deadlines to respond.

The first international flight to leave conflict-hit Chechnya in 15 years has taken off from the airport in Grozny.

The Boeing 757 left with 200 pilgrims travelling to Muslim holy sites in Saudi Arabia.

The flight was seen off at the airport by Chechnya’s Kremlin-backed leader, Ramzan Kadyrov.

An official statement said seven aircraft would carry 2,000 pilgrims to Saudi Arabia, and regular international flights would begin soon.

“Today’s event is a big success for our people,” Mr Kadyrov said.

Difficult journeys

He paid tribute to those who had made a difficult journey from other parts of the region to reach Grozny for the flight.

Mr Kadyrov said he hoped the resumption of international flights would boost Chechnya’s economy.

Moscow decided to lift all restrictions on international flights from Grozny earlier this month.

The move followed Moscow’s announcement in April that anti-terrorist operations in Chechnya were to end as stability had returned.

Russian forces fought two conflicts with separatists in Chechnya in the 1990s and sporadic violence in Russia’s North Caucasus region has continued.

In recent months, human rights activists have been the target of kidnappings and killings.

President Obama, taking questions Monday from government-selected students at a town hall-style meeting in Shanghai, called himself “a big supporter of non-censorship.” But the Beijing government, apparently, is not, and most Chinese never got to hear or read what Obama said.

His talk to the students was never mentioned on China’s main official 7 p.m. news broadcast. The session was broadcast live only on a single small Shanghai television station — and that station’s Web site switched to a children’s program instead of live-streaming the president’s event. And most news Web sites deleted stories about Obama taking a question on Internet freedom.

The 7 p.m. news broadcast of CCTV is the most influential in China, reflecting the official government line and serving as the main source of television news for most people outside the major cities. But Obama’s arrival in Shanghai was not even the lead story — it was seventh in a line of stories that began with one on President Hu Jintao returning from the Asia Pacific Economic Cooperation forum in Singapore.

When CCTV did mention Obama’s visit, well into the broadcast, it was in a story of less than a minute that just noted his airport arrival and his meeting with the mayor of Shanghai. There was not a word about the forum with students, which the White House had billed as the marquee event of Obama’s first trip to China.

Obama was asked what he thought about the Chinese government blocking several Internet international sites, such as Facebook, Twitter and YouTube, as well as critical news sites. “I’ve always been a strong supporter of open Internet use,” Obama said. (
The question, and Obama’s answer, appeared almost immediately as a top news story on the official New China News Agency, known here as Xinhua, as well on as several popular Chinese Web sites.

But about an hour later, the stories about Obama embracing Internet freedom disappeared.

The sina.com site, for example, initially ran the story under the headline: “Obama: The Internet is a tool for becoming stronger and citizens can participate.” An hour later, anyone going to that link got the message, “Cannot find the page.”

The news was also deleted from Xinhua, which initially posted a story about Obama’s answer on Internet censorship but later carried a notice that said, “Sorry! The news you are checking has been deleted or expired.”

Even the students who posed questions to Obama were pre-selected, and most appeared to be members of the Chinese Communist Party Youth League. Afterward, some of them, when contacted by a reporter, criticized Obama’s statements about Internet censorship, even while saying they were generally pleased having seen the U.S. president up close. I strongly disagree with what Obama said about the Internet firewall,” said Tao Weishuo, a 24-year old postgraduate student from Fudan University. “I think all Chinese people have Internet freedom — we can speak out freely on the Internet about current social affairs.” He said the question to him came from a Web site outside China.

Still, Tao said he was impressed. “I think he is kind and warm,” Tao said.

Guo Ruijie, a senior majoring in English at Tongji University, said Obama “doesn’t have big president airs. When he gave his speech on the stage, he was walking around like going for a walk with his caged birds. He gave me the impression that he is very amiable and easy to approach and close to people, and he cares a lot about the next generation.”

While Obama was speaking inside, a small group of fans waited outside hoping for a glimpse of the president or his motorcade. They included Chinese students and some young Americans studying in China.

“I really agree with Obama’s slogan, ‘change’ ” said Jiang Yimeng, 19-year-old high school graduate. “I think the U.S. is more open than China. I’m now applying to universities in the United States. I really want to go to the George Washington University, which is just opposite the White House.”

She added, “I also heard that the White House is open to public, and normal people can actually see president and his family close up. Obama is so charming and always smiling.”

Shi Tingchong, also 19 and a high school graduate, spent a year as an exchange student in Ohio.

“I’m here because I worship him,” she said. “I think he is someone who can really listen to us. Chinese government leaders just read from what’s written down on documents.”

She added, “He is a great black president. After I read his book, ‘Dreams From My Father,’ I think his road to success was really not easy, and he couldn’t achieve success without his excellent eloquence.”

Washington Post researchers Liu Liu in Shanghai and Zhang Jie in Beijing contributed to this report.