Los Angeles - A relatively well-behaved Britney Spears wowed a crowd packed with superstars when she made a not-so-surprise appearance at Madonna's concert in Los Angeles Thursday night.

Wearing what the Los Angeles Times described as a demure tuxedo- style shirt, pants and black heels, Spears introduced herself with a take from her last album: "It's Britney Bitch."

She then sang along with Madonna on the last verse of the track Human Nature, to the delight of the crowd, which included Jennifer Lopez, Ryan Seacrest, Heidi Klum, Drew Barrymore, Fergie and Donald Sutherland.

San Francisco - Shares of ailing internet pioneer Yahoo plunged more than 10 per cent Friday after Microsoft CEO Steve Ballmer reiterated that his company was not interested in reviving its takeover bid.

Yahoo CEO Jerry Yang this week urged Microsoft to buy the company, just a day after Google said it was dropping plans for an advertising alliance with Yahoo, which would have boosted Yahoo's income by up to 400 million dollars per year.

San Francisco - Obama fever may have swept the world, following the Democratic presidential candidate's historic election victory Tuesday. Now millions of computer users are under threat from an Obama virus, network security companies said Friday.

Authors of the virus are hoping to benefit from the huge interest in US president-elect Barack Obama, with an avalanche of spam messages purporting to offer news of his victory.

Port-au-Prince - A school building collapsed Friday near Haitian capital Port-au-Prince and several casualties were feared, Red Cross officials involved in rescue efforts said.

The children were in their classrooms at the time of the collapse in Petionville, just outside the capital, Michaele Gedeon, president of Haiti's Red Cross told CNN. "The whole school collapsed on the kids," she said.

The cause of the collapse was not known.

Brussels - Italian Prime Minister Silvio Berlusconi on Friday refused to apologise for calling US president-elect Barack Obama "sun-tanned."

The outspoken premier was approached at a European Union summit in Brussels by a US journalist, who had asked him to say sorry for offending Obama with the racial slur.

"It is you who should be apologizing to Italy," an angry Berlusconi retorted before abandoning a press conference midway.

Brussels - After leading the way in responding to the world financial crisis, Europe could be facing headwinds as it attempts to press on with a rapid and comprehensive overhaul of the global finance sector.

Gone are the high-minded calls for sweeping changes to the international financial system as proposed only a few weeks ago by French President Nicolas Sarkozy when panic selling engulfed share markets and sent shock waves across the world economy.