WIKILEAKS founder Julian Assange has described re-elected President Barack Obama as a "wolf in sheep's clothing" and says he expects the US government to keep attacking the anti-secrecy website.

Speaking by phone from Ecuador's London embassy, where he sought asylum in June in a bid to avoid extradition to Sweden over sex crime allegations, Assange said on Wednesday Obama's victory was no cause for celebration.

"Obama seems to be a nice man, and that is precisely the problem," the 41-year-old Australian told AFP, after the president defeated Republican Mitt Romney on Tuesday night to sweep back into the White House.

"It's better to have a sheep in wolf's clothing than a wolf in sheep's clothing."

Assange complained of the "persecution" of WikiLeaks by Obama's government.

He added: "All of the activities against WikiLeaks by the United States have occurred under an Obama administration.

"The Republican party has not been an effective restraining force on government excesses over the last four years.

"There is no reason to believe that will change - in fact, the Republicans will push the administration into ever greater excesses."

Assange urged the United States to free Bradley Manning, the soldier accused of leaking a huge cache of classified military documents to WikiLeaks and has been held in solitary confinement in a military prison for over two years.

"The re-election of Barack Obama coincides with the 899th day of Bradley Manning's confinement," Assange said.

WikiLeaks enraged Washington in 2010 by leaking hundreds of thousands of classified US documents on the wars in Iraq and Afghanistan and embarrassing diplomatic cables from US embassies around the world.

Assange was arrested that same year.

He denies the allegations of rape and sexual assault and claims that if he is extradited to Sweden he could be passed on to the US and prosecuted, facing treatment similar to Manning's or even the death sentence.

Ecuador granted Assange asylum on August 16 but Britain has refused to grant him safe passage out of the country - leaving the two governments in diplomatic deadlock and Assange stuck inside the embassy.

He faces immediate arrest if he attempts to leave the building in London's plush Knightsbridge district.

Assange said there had been "no formal progress" in recent weeks on a diplomatic solution to his confinement in the embassy, but said WikiLeaks' strategy on ending the stalemate was "moving from defence to offence".

Asked what this involved, he said: "It will become clear in the coming months."

Assange, who sounded hoarse, refused to comment on his health after Ecuador said last month it had requested a meeting with British officials to discuss claims Assange was losing weight and suffering vision problems.