Julian Assange, the WikiLeaks founder wanted in Sweden over accusations of sexual assault, will launch a fresh appeal on Tuesday against his extradition at the high court in London.

The Australian will begin the latest stage of his legal challenge against attempts to send him to Sweden to face charges relating to alleged incidents with two women during a trip to Stockholm in August 2010. One accusation, that he had sex with a woman while she was asleep, would amount to rape under Swedish law if proved. Both women had previously had consenting sex with Assange. He denies any wrongdoing.

Swedish authorities secured a European arrest warrant in December and shortly afterwards he was detained by British police and bailed. At his first appeal in February, Westminster magistrates court – sitting at Belmarsh – ordered that he should be extradited, despite his defence alleging he would not get a fair trial and that the extradition attempt was politically motivated. The arrest warrant came as WikiLeaks was releasing thousands of classified US diplomatic cables it had obtained through a whistleblower.

Assange's legal team argued that the conduct of the Swedish prosecutor amounted to an "abuse of process" because the allegations against him were initially dismissed and then reopened, the prosecutor had refused Assange's offer of an interview and documents had not been made available to him in English. They also claimed the Swedish prosecutor, Marianne Ny, was "biased against men". Westminster magistrates found against Assange and ordered his extradition to Sweden.

Assange has claimed this would make it easier for US authorities to seek his extradition to face possible charges over his release in 2010 of hundreds of thousands of classified documents including the US diplomatic cables and military logs from Afghanistan and Iraq. Before their unsuccessful appeal in January, Assange's legal team warned there was "a real risk" he could face the death penalty in the US or detention in Guantánamo Bay.

Assange has appointed a new legal team for Tuesday's hearing. His previous representative, media lawyer Mark Stephens, has been replaced by Gareth Peirce, who has represented the Guildford Four, the Birmingham Six and Moazzam Begg, a British Muslim who was held at Guantánamo. Ben Emmerson QC, who specialises in European human rights law, will be Assange's barrister, replacing Geoffrey Robertson QC, who acted for him in January.

The changes are thought to be part of a more conciliatory approach by Assange. Peirce's office would not comment on their strategy on Monday, but she has been previously quoted indicating the need for sensitivity and respect in the case.

"Each of the human beings involved deserves respect and consideration," she reportedly wrote to former US senator Tom Hayden for an article in the Nation, a US magazine. "It is hoped that whatever steps as are required to be taken in the future will be taken thoughtfully, with sensitivity and with such respect."

Assange recently filmed an online fundraising advert in which he appeared to take credit for inspiring the uprising in Egypt. The commercial spoofs the MasterCard ads, saying: "Fighting legal cases across five countries: $1m" and "added cost due to house arrest: £500,000" before concluding with Assange watching footage on his laptop of Egyptian protesters streaming towards Tahrir Square with the voiceover: "Watching the world change as a result of your work: priceless. There are some people that don't like change. For everyone else there is WikiLeaks."

WikiLeaks issued a statement in June marking Assange's six months under house arrest at Ellingham Hall in Norfolk, the 10-bedroom country home of Vaughan Smith, founder of the Frontline club in London. Assange celebrated his 40th birthday there on Sunday with about 100 guests.

WikiLeaks said Assange had not been charged with a crime in any country and complained his conditions were "excessive and dehumanising".

The case will be heard by Lord Justice Thomas and Mr Justice Ouseley in court four of the Royal Courts of Justice and will begin at 10.30am. It is scheduled to last for two days. If Assange loses the case he could yet appeal to the supreme court.