London (CNN) -- WikiLeaks editor-in-chief Julian Assange has asked an appeals court to block his extradition to Sweden from the United Kingdom to face questioning on sexual misconduct allegations.
Lawyers for Assange told the court Tuesday that the European arrest warrant on which their client is being held was not a "fair and accurate description" of the facts of the case.
If the case had been accurately described, his lawyers said, the judges would see that the allegations did not constitute a crime under UK law.
Assange is fighting the case in London's High Court after a judge at Belmarsh Magistrates' Court ruled in February that the WikiLeaks head should be extradited.
Assange did not speak going in to the hearing, and his lawyers said they would not make comments before the appeal began.
The case is not related to the work of Assange's website, which facilitates the publication of secret information. It made headlines last year for leaking documents and videos related to the wars in Iraq and Afghanistan, and thousands of U.S. diplomatic cables.
At a news conference after the magistrate judge's extradition ruling on February 24, he lashed out at the decision to send him to Sweden.
He said to thrust someone into a foreign land where someone does not speak the language or understand the judicial system "is a very grave matter."
Assange has not been charged with a crime, but Swedish prosecutors want to question him in connection with sexual misconduct allegations related to separate incidents in August.
Assange denies the accusations, saying they are an attempt to smear him. His attorneys are fighting his extradition on procedural and human-rights grounds.
Judge Howard Riddell, however, dismissed almost all the arguments made by the defense as he made his decision in February.
He ruled that the allegations against Assange are extraditable offenses.
He disagreed with Assange's lawyers that Swedish prosecutors did not have the authority to issue a European arrest warrant and ruled that the warrant was valid.
Riddell also tossed out claims that Assange would not be able to obtain a fair trial in Sweden or that Swedish prosecutors had not made any effort to promptly interview Assange before he left Sweden last year.
"In fact this is untrue," the judge said in the ruling. He said Assange's Swedish lawyer had made a "deliberate attempt to mislead the court" and that it was Assange who had avoided interrogation before he left Sweden.
"It would be a reasonable assumption from the facts that Mr. Assange was deliberately avoiding interrogation before he left Sweden," Riddell wrote.
Assange's lawyers have raised the possibility that Sweden would hand him over to the United States if Britain extradites him to Sweden.
The prosecutor representing Sweden has dismissed that claim.
CNN's David Wilkinson and Andrew Carey contributed to this report.