Lawyers for Assange immediately said they would appeal against the decision, which they fear could eventually result in Assange facing imprisonment in the US.

London -- WikiLeaks founder Julian Assange can be extradited to Sweden to face rape charges, a British judge ruled on Thursday after throwing out defense arguments that he would face an unfair trial.

Lawyers for Assange immediately said they would appeal against the decision, setting up a lengthy legal battle through Britain's courts that could postpone the 39-year-old Australian's ultimate fate for months.

"As I am satisfied that extradition is compatible with the defendant's (European) Convention rights, I must order that Mr Assange be extradited to Sweden," judge Howard Riddle said.

Speaking after the hearing at the top security Belmarsh Magistrates' Court in southeast London, Assange criticized the European system under which he was detained in December at Sweden's request.

"It is a result of the European Arrest Warrant system run amok. There was no consideration during this entire process as to the merits of the allegations against me," he told around 100 journalists from across the globe.

Assange has seven days to lodge a formal appeal. The judge gave him bail on the same conditions as before, namely that he should reside at a friend's mansion in eastern England, wear an electronic ankle tag and observe a curfew.

Celebrity backers including socialite Jemima Khan and rights campaigner Bianca Jagger also attended the hearing. Several dozen supporters, some of them in orange Guantanamo Bay-style jumpsuits, demonstrated outside the court.

Assange rocked the world's diplomatic institutions and infuriated Washington last year when his whistleblowing website began releasing hundreds of thousands of secret US State Department and military documents.

The former computer hacker says the claims against him by two women he met during a seminar organized by WikiLeaks in August last year are politically motivated because of his work.

Assange's Swedish lawyer Bjorn Hurtig made a "deliberate attempt to mislead the court" when he said that he had been unable to contact Assange to arrange an interview with Swedish prosecutors, he added.

Judge Riddle also rejected claims that Assange could not face a fair trial as some evidence would be held behind closed doors, and that it was possible he would be re-extradited to the United States where he could face the death penalty.

His lawyer Mark Stephens criticized the "tick-box justice" of the warrant system, but added: "We still remain very optimistic about our opportunities on appeal."

Claes Borgstrom, the lawyer for the two Swedish women at the center of the claims, said it was "regrettable" that Assange was appealing but that he hoped the case would be over by summer.

"Assange must respect the principles that he has expressed about WikiLeaks and take responsibility," he told the Swedish news agency TT.

The United States said the case was solely a matter for Britain and Sweden.

"Notwithstanding claims to the contrary, the US is not involved," State Department spokesman Philip Crowley said in a Twitter message.

Assange has claimed his greatest fear was eventual extradition to the United States, where his lawyers argued he could be sent to the Guantanamo Bay detention facility or face the death penalty.

WikiLeaks last November began publishing around 250,000 US diplomatic cables. It has also leaked thousands of secret documents about the wars in Afghanistan and Iraq.

The mother of Wikileaks founder Julian Assange condemned Thursday a court order for his extradition to Sweden as "political and legal gang rape", the Australian Associated Press reported.

"I would say that what we're looking at here is political and legal gang rape of my son," AAP quoted Christine Assange as saying.

"It's a real David and Goliath situation," she said.

"You've got misuse of the European arrest warrant, first time ever that it's been used this way."

"What Julian through his site is proving (is) the need for WikiLeaks," his mother said. "I'm, obviously, scared for him as a mother but the world ought to be scared for its democracies."

She said that she had expected the extradition order, and that her son felt abandoned by the Australian government.

"The greatest fear I have is that the Western world in its effort to shut up someone who's telling the truth to the people of their countries will breach every piece of legislation in order to get him and will co-operate across borders to do so."