WikiLeaks founder Julian Assange appeared in court Monday for a showdown with Swedish authorities to fight an extradition bid over sex crimes allegations.

Assange, wearing a blue suit, was flanked by two prison guards as the hearing opened at Belmarsh Magistrates' Court. Celebrity supporters Jemima Khan and Bianca Jagger, and politician Tony Benn also attended.

Assange is accused of sexual misconduct by two women he met during a visit to Stockholm last year. Defense lawyers will argue that he should not be extradited because he has not been charged with a crime, because of flaws in Swedish prosecutors' case — and because a ticket to Sweden could eventually land him in Guantanamo Bay or on U.S. death row.

American officials are trying to build a criminal case against the secret–spilling site, which has angered Washington by publishing a trove of leaked diplomatic cables and secret U.S. military files. Assange's lawyers claim the Swedish prosecution is linked to the leaks and politically motivated.

Preliminary defense arguments released by Assange's legal team claim "there is a real risk that, if extradited to Sweden, the U.S. will seek his extradition and/or illegal rendition to the USA, where there will be a real risk of him being detained at Guantanamo Bay or elsewhere."

The document adds that "there is a real risk that he could be made subject to the death penalty" if sent to the United States. Under European law, suspects cannot be extradited to jurisdictions where they may face execution.