LONDON - WikiLeaks founder Julian Assange on Sunday received a rapturous reception during a carefully staged appearance on the balcony of Ecuador's London embassy, where he has taken refuge for two months.

Supporters, who numbered around 200 when Assange took to the microphone shortly after 2:00 pm (1300 GMT), clapped and chanted through a megaphone outside the embassy in the upmarket Knightsbridge neighbourhood.

Around 150 of the world's press also gathered at the site to hear from the man at the centre of a diplomatic storm between Britain and Ecuador.

As anticipation grew before Assange's appearance, the atmosphere on the street resembled a rock concert as activists cheered while former Spanish judge Baltasar Garzon and the leftist intellectual Tariq Ali took to the loudspeaker.

"I have spoken to Julian Assange and I can tell you he is in fighting spirits and he is thankful to the people of Ecuador and especially to the president for granting asylum," said Garzon.

"Julian Assange has always fought for truth and justice and has defended human rights and continues to do so," he added.

Messages from supporters including fashion designer Vivienne Westwood and film-maker Ken Loach were read out to the impatient public.

As the wait dragged on, a WikiLeaks activist on the balcony started a countdown, signaling to the crowd "five minutes" then "one minute" to go.

When the moment arrived, the small street bordering the famous Harrods department store was packed, with police forming a security cordon to contain the crowd.

"Can you hear me?" asked the day's star turn, eliciting loud cheers from his supporters.

The founder of the whistle-blowing website reminded the audience of the "threat" made by Britain that it could storm the embassy. He also thanked activists who maintained a constant vigil outside the building, saying "the world is watching because you are watching!"

It was the first time in months that Assange has mobilized such crowds as support waned during his two-year failed judicial challenge to remain in Britain and avoid extradition to Sweden for questioning over rape and sexual assault allegations.

Ironically, it seems that it was Britain's threat to invoke a 1987 law to remove Assange from the embassy which has brought the former computer hacker back into the media spotlight.

Ecuadoran supporters outside the embassy chanted "the people united will never be defeated", and were later joined by English sympathisers.

By uniting his cause with leftist anti-capitalist movements such as "Occupy", Assange has successfully expanded his circle of supporters.

He also brought up the case of Pussy Riot, the Russian female punk rock group who saw three band members sentenced this week to two years in prison for singing anti-Vladimir Putin songs in a Moscow cathedral.

Assange called on President Barack Obama to end the US "witch-hunt" against his whistleblowing website in a speech from the balcony of his refuge in Ecuador's London embassy.

The 41-year-old Australian walked into the embassy in June seeking asylum after exhausting all legal avenues in Britain to stop his being extradited to Sweden, where he is wanted for questioning over alleged sex crimes.

"I ask President Obama to do the right thing, the United States must renounce its witch-hunt against WikiLeaks," said Assange in his first public comments since being granted political asylum by Ecuador on Thursday.

Assange praised the "courage" shown by the Latin American nation's President Rafael Correa in giving him sanctuary, a move that has angered Britain which has said it would continue to seek his extradition.

However, at no time in Assange's statement, or in those of his supporters, was the Swedish case mentioned, nor did he indicate what his next move might be as he cannot leave the Ecuadoran embassy without risking arrest.