WikiLeaks founder Julian Assange has called on US President Barack Obama to end a so-called "witch hunt" against his secret-spilling website.

Mr Assange appeared in public today for the first time since he took refuge two months ago inside Ecuador's Embassy in London.

He is avoiding extradition to Sweden on sex crimes allegations.

The 41-year-old Australian has fought for two years against efforts to send him to Sweden for questioning over alleged sexual misconduct against two women.

He addressed several hundred supporters and reporters as he spoke from the small balcony of Ecuador's mission, watched by dozens of British police.

Ecuador's President Rafael Correa last Thursday granted Mr Assange asylum and he remains out of reach of British authorities while he is inside the country's embassy.

Britain insists that if he steps outside, he will be detained and sent to Sweden, as by law it must meet the obligations of a European arrest warrant.

Mr Assange and his supporters claim that the Swedish case is merely the opening gambit in a Washington-orchestrated plot to make him stand trial in the US over his work with WikiLeaks.

This is disputed by both Swedish authorities and the women involved.

"I ask President Obama to do the right thing. The United States must renounce its witch hunt against WikiLeaks," Mr Assange said as he read aloud a written statement.

"The United States must dissolve its FBI investigation. The United States must vow that it will not seek to prosecute our staff or our supporters."

He said that in purportedly targeting WikLeaks, the US risked "dragging us all into a dark, repressive world in which journalists live under fear of prosecution."

A Virginia grand jury in the US is studying evidence that might link Mr Assange to Pfc Bradley Manning, the US soldier who has been charged with aiding the enemy by passing the secret files to WikiLeaks and is awaiting trial.

No action against Mr Assange has yet been taken.

Mr Assange also urged the US to release Pfc Manning, but said: "If Bradley Manning really did as he is accused, he is a hero, an example to us all, and one of the world's foremost political prisoners."

The WikiLeaks founder did not refer in his statement to the Swedish allegations against him, or indicate how he believes the stalemate over his future may be resolved, though he said he hoped to be "reunited soon" with his two children.

Mr Assange said Ecuador had shown itself to be "courageous" in granting him refuge.

He also claims to have won support from other Latin American, Central American and South American nations, including Brazil, Chile, Mexico and Argentina.

Speaking outside the embassy, former Spanish Judge Baltasar Garzon, who is representing Mr Assange, said Ecuador could consider making an appeal to the International Court of Justice in The Hague to compel Britain to grant Mr Assange safe passage out of the country.

Judge Garzon, who won global fame for aggressively taking on international human rights cases, is appealing his conviction for overstepping his jurisdiction in a domestic corruption probe in Spain.

Tensions rise

Tensions have risen between London and Quito over the Assange case, after Britain appeared to suggest it could invoke a little-known law to strip Ecuador's Embassy of diplomatic privileges.

The law could allow British police to move in and detain Mr Assange in Ecuador's embassy.

Mr Assange claimed Britain had only refrained from carrying out the threat because of the presence of his supporters outside the embassy.

Ecuador's mission is a small apartment inside a larger building which houses offices and Colombia's Embassy.

Under the 1961 Vienna Convention on Consular Relations, diplomatic posts are treated as the territory of the foreign nation.

Britain's government declined to comment on Mr Assange's statement, though diplomats have accused Ecuador of deliberately misinterpreting its attempts to explain its legal options, and insist they are seeking an amicable solution to the standoff.

The WikiLeaks founder attempted to draw parallels between himself and the Russian punk band Pussy Riot, three of whose members were convicted and jailed this week for a performance denouncing President Vladimir Putin in a Moscow cathedral.

He shot to international prominence in 2010 when his WikiLeaks website began publishing a huge trove of American diplomatic and military secrets, including 250,000 US embassy cables that highlight the sensitive, candid and often embarrassing backroom dealings of US diplomats.

As he toured the globe to highlight the disclosures, two women accused him of sex offences during a trip to Sweden.

Mr Assange denies any wrongdoing, and insists sex with the women was consensual.