London, July 12 (IANS) WikiLeaks founder Julian Assange Tuesday challenged in the London high court his extradition to Sweden in a sexual assault case. He termed the allegations as "legally flawed", a media report said.

Lawyers for Assange challenged a ruling by the Belmarsh magistrates' court that extradition should go ahead, the Independent reported.

Ben Emmerson - appearing for the 40-year-old Assange - told the court the European Arrest Warrant on which the WikiLeaks founder was being held was flawed because it failed to provide "a fair, accurate and proper" description of the alleged sexual misconduct.

He said Assange was a victim of a "philosophical and judicial mismatch" between English and Swedish law on what constituted sex crimes.

The extradition order was also flawed because it sought Assange's return to Sweden "not for prosecution but for the purposes of an investigation".

Emmerson argued that using extradition for the limited purpose of an investigation amounted to "a disproportionate utilisation" of the European Arrest Warrant system.

Assange claims the allegations are politically motivated, particularly after WikiLeaks published the leaked US diplomatic cables.

He, however, said nothing when he arrived at the high court Tuesday.

Assange recently hosted a lavish 40th birthday party at the mansion in Norfolk where he is being kept under house arrest.

Although not charged, he is wanted by the Swedish prosecution authority to answer questions on allegations of sexual assault, said to have been committed in Stockholm in August last year. The accusations were made by two women WikiLeaks volunteers.

Assange has expressed fear that extradition to Sweden could be a stepping stone to being sent to the US to stand trial on charges related to WikiLeaks, and that he could even face the death penalty.

Assange got bail in December but is required to wear an electronic ankle tag and check in daily at a nearby police station.