Defence attorneys for Julian Assange, the founder of WikiLeaks, has said he could end up facing the death penalty in the US if the UK extradites him to Sweden, where he is accused of sex crimes.
The lawyers fear that Sweden will in turn hand him over to the US.
Following Assange's appearance in a London court on Tuesday, his attorneys published an outline of the defence he will use at a full extradition hearing scheduled for February 7.
"There is a real risk that, if extradited to Sweden, the US 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" according to a legal memo on the website of the law firm Finers Stephens Innocent.
"Indeed, if Mr Assange were rendered to the USA, without assurances that the death penalty would not be carried out, there is a real risk that he could be made subject to the death penalty."
The Australian citizen, who has angered the US and other states by releasing embarrassing classified US diplomatic cables, is wanted by Sweden for questioning over alleged sexual offences against two women in Sweden last summer.
According to his lawyer, the allegations stem from a dispute over "consensual but unprotected sex".
'Risk of torture'
The legal memo added that if Assange ended up in the US, there is "a real risk" he would be subject to ill-treatment or even torture.
The US has not yet filed any charges against Assange, but officials are investigating whether he can be prosecuted under American espionage laws.
Under a legal agreement on extraditions between Sweden and the US, Assange would have to be charged in the US with a crime carrying a minimum of two-year prison term under both countries' laws.
Military or political crimes are not valid grounds for extradition.
As Assange would first have to be extradited from the UK to Sweden, the latter cannot extradite him to a third country unless the UK gives its approval.
Extraditions from Sweden to countries outside the European Union are relatively rare. Between 2007-2009, 14 people were extradited to countries outside the EU and the Nordic Countries.
The Swedish government takes the final decision on extraditions, and can decide not to have a person handed over even if there is legal ground for it. However, the government cannot have someone extradited if the legal requirements are not met.
Under European human rights conventions, the government cannot extradite a person to a country where the individual may face death penalty or ill-treatment.
Pointing to a dent in Sweden's human rights record, Assange's lawyers mentioned a case in 2001 in which two asylum seekers were deported from Sweden.
The Swedish government was heavily criticised both domestically and by the UN human rights committee for the rough treatment of Ahmed Agiza and Muhammad Al-Zery, who the Swedish intelligence agency suspected of having links to an al-Qaeda affiliated organisation.
Before the deportation, Sweden had negotiated guarantees from Egypt that the men would not be tortured or executed. However, strong allegations emerged that both men were tortured after they were transported to Egypt in a CIA plane with masked American agents.
Extradition 'unlawful'
Besides the alleged threat of mistreatment in the US, Assange's defence listed a number of other reasons as to why an extradition from the UK to Sweden would be "unlawful".
Lawyers questioned whether Marianne Ny, the Swedish director of prosecution, had the legal right to issue a European arrest warrant, and if there was legal ground for a warrant to be issued "for the purpose of merely of questioning him in order to further [Ny's] investigation".
The spokeswoman for the prosecutor's office maintained that Ny had the right under Swedish law to issue to arrest order but declined to comment on the second claim.
The document also questioned whether the alleged crimes really amount to extradition offences, arguing that "none of the conduct alleged against the requested person would constitute an offence in England and Wales."
Assange was jailed in the UK in December after the Swedish prosecutor issued a European arrest warrant seeking his extradition. He was released on $370,000 bail nine days later.
As part of his bail conditions, Assange must remain for the most part at the home of a journalist associate in eastern England, abide by a curfew, report to police daily and wear an electronic tag.
After Tuesday's court hearing, Assange said his organisation would press ahead with its release of documents despite his own legal battle.
"Our work with WikiLeaks continues unabated and we are stepping up our publishing for matters related to Cablegate and other materials," Assange told reporters outside the court.
"Those will shortly be appearing through our newspaper partners around the world - big and small newspapers and some human rights organisations."
