Wikileaks founder Julian Assange has urged the US to end its "witch hunt" of his organisation and described threats of prosecution of whistleblowers as "foolish".
Mr Assange, making a televised statement from the Ecuadorian embassy in central London where he has taken asylum to avoid deportation to Sweden, said Ecuador has taken "a courageous stand for justice".
He said the United States risked shunting the world into an era of journalistic oppression.
"As Wikileaks stands under threat, so does the freedom of expression and the health of all of our societies," Mr Assange said. "I ask President Obama to do the right thing: the United States must renounce its witch-hunt against Wikileaks."
Britain says it will not allow the anti-secrecy campaigner to travel to South America because it is obliged to extradite him to Sweden, where he is wanted for questioning over rape and sexual assault allegations.
To allow Mr Assange to avoid arrest by stepping outside the embassy, a balcony door on an upper floor was removed, leading up to his first public appearance since seeking refuge in the diplomatic mission two months ago.
Speaking behind the condor of the Ecuadorean coat of arms on the white balcony railing of the embassy, Mr Assange thanked president Rafael Correa and Ecuador's diplomats, whom he praised for standing up against oppression.
"The sun came up on a different world and a courageous Latin American nation took a stand for justice," Mr Assange said from the balcony.
Mr Assange's attempt to escape extradition has touched off a diplomatic tussle between Britain and Ecuador, which accused London of threatening to raid its embassy and casting the dispute as an arrogant European power treating a Latin American nation like a colony.
Ecuador has cast its dispute with Britain over asylum for Mr Assange as a struggle against colonialism, drawing growing support from its neighbours in the international diplomatic saga.
Incensed by London's threat to break into the Ecuadorean Embassy, Mr Correa's government has accused Britain of bullying and has formally granted Mr Assange asylum.
Trying to present the affair as an international David versus Goliath battle, Ecuador was hosting this weekend foreign ministers from both the ALBA group of leftist-led Latin American nations and the Union of South American Nations (UNASUR).
"They're out of touch. Who do they think they're dealing with? Can't they see that this is a dignified and sovereign government which will not kneel down before anyone?" Mr Correa said in his weekly address last night.
"What a mentality, eh? They have not realized that Latin America is free and sovereign and that we'll not put up with meddling, colonialism of any kind, at least in this country, small, but with a big heart."
Yesterday, Venezuelan president Hugo Chavez called for ALBA members - which also include Nicaragua and communist-ruled Cuba, among others - to stand behind Ecuador.
"Latin America must be respected, our people must be respected, but only united can we earn that respect," he said.
Support for Ecuador appears to be growing in the region.
"Britain ... is wrong. The threat is not only an aggression to Ecuador, it's against Bolivia, it's against South America, against the whole of Latin America," Bolivian President Evo Morales said.
Ecuadorean state media said other nations including Colombia and Argentina were backing Correa's position.
Representatives of the hemispheric Organisation of American States (OAS) called for a foreign ministers' meeting next week over the Assange affair.
Canada and the United States voted against holding the meeting.
"The central issue is not the right of asylum, it is the inviolability of embassies," OAS secretary general Jose Miguel Insulza said after the vote.
Ecuador, an oil-producing nation of 14.5 million people that seldom finds itself in the global spotlight, is furious Britain said it could make use of an obscure measure to break into its embassy where Mr Assange has been for more than two months.
"Is the threat of a European government to the sovereignty of a South American country not important because we're a small nation?" Ecuadorean foreign minister Ricardo Patino said, adding that maybe the region should also discuss the US Guantanamo base in Cuba and Argentina's claim to the Falklands.
The Ecuadorean government shares Mr Assange's fears that he ultimately could be extradited to the United States, which is angry that his WikiLeaks website has leaked hundreds of thousands of secret US diplomatic and military cables.
The leftist Correa, who has high popularity levels and is expected to run for re-election in February 2013, had developed some rapport with Mr Assange during an online interview the WikiLeaks founder did with him this year.
Mr Correa's stance has been largely cheered by Ecuadoreans, and there have been scattered protests at the British Embassy.
"The whole world should back Ecuador for giving Assange asylum and because this country is the first one to promote freedom of expression," said Mary Valenzuela (39), a restaurant owner.
After WikiLeaks released the diplomatic cables that laid bare Washington's power-brokering across the globe, Mr Assange became known as a freedom-of-speech champion in many parts of Latin America, where there is strong tradition of criticizing the United States for meddling.
Leftist nations, and others, have been increasingly turning to new partners like China and Russia in recent years.
Reuters, Bloomberg