Lawyers representing the WikiLeaks founder, Julian Assange, have lodged papers to appeal against his extradition from Britain to Sweden to face allegations of rape and sexual assault.

The high court in London confirmed it had received documents to challenge the ruling made at Belmarsh magistrates court, south London, last week. No date has been set for a hearing.

The 39-year-old Australian had always planned to appeal if he failed to escape the European arrest warrant (EAW) at the first attempt. He faces being sent to Sweden within 10 days if his appeal is unsuccessful.

Last week Assange dismissed the decision to extradite him as a "rubber-stamping process". It came as no surprise, he said, but was wrong. "There was no consideration during this entire process as to the merit of the allegations made against me, no consideration or examination of even the complaints made in Sweden and, of course, we have always known we would appeal."

He has been fighting extradition since he was arrested and bailed in December, and has consistently denied the allegations, made by two women in August last year.

Assange's lawyers argued he would not receive a fair trial in Sweden. They said the warrant was invalid because he had not been charged with any offence and the alleged assaults were not grounds for extradition. Assange fears removal to Sweden will make it easier for Washington to extradite him to the US on possible charges relating to WikiLeaks's release of the US embassy cables. The US has been investigating the WikLeaks website, although no charges have been laid. Sweden would have to ask the UK for any onward extradition.

Assange faces four allegations, the most serious that, during a visit to Stockholm, he had sex with a woman, Miss B, while she was sleeping, without a condom and without her consent. Three counts of sexual assault are alleged by another woman, Miss A. If found guilty of the rape charge he could face up to four years in prison.

Howard Riddle, the chief magistrate at the extradition hearing, acknowledged "considerable adverse publicity" against Assange in Sweden but said if there had been any irregularities in the Swedish system the best place to examine them was in a Swedish trial.