WikiLeaks founder Julian Assange asked judges in the High Court in London on Monday to allow him to continue his legal battle to avoid extradition to Sweden over allegations of rape and sexual assault.

Almost a year since he was arrested in London on a warrant issued by Sweden, the 40-year-old head of the whistleblowing website is seeking permission from judges to allow his appeal to proceed to the Supreme Court.

As the lengthy case enters what could be its final chapter in Britain, Assange arrived at the court dressed in a grey coat and white shirt and exchanged muted greetings with his supporters.

If the High Court judges refuse his appeal, Assange could be extradited within 10 days to Sweden, where authorities want to question him over allegations made by two women dating back to August 2010.

For the appeal to be transferred to the Supreme Court, the judges must rule that the case raises a question of general public importance.

Monday's hearing comes a month after the former hacker lost his first appeal against deportation.

Assange claims the allegations are politically motivated and linked to WikiLeaks' release of hundreds of thousands of classified US files detailing the wars in Iraq and Afghanistan, which infuriated Washington.

Later releases of files outlining US diplomats' cables from embassies across the world further embarrassed the US administration.

The Australian former computer hacker has spent much of the last year on a supporter's country estate in eastern England, living under stringent bail conditions that amount to virtual house arrest.

A lower court initially approved Assange's extradition in February, but he appealed to the High Court which rejected his challenge on November 2.

Legal sources have said a decision was expected Monday, but cautioned that such an outcome was not certain.

According to the website Sweden vs. Assange, which supports his case, his legal team will question whether a European arrest warrant issued by a state prosecutor -- in this case in Sweden -- is valid.

They will also query whether he can be defined as "accused" despite having not been prosecuted, the website added.

Support for the platinum blond WikiLeaks chief has dwindled amid a slew of controversies, including a spectacular falling-out with the organisation's former media partners, the New York Times and the Guardian.

Former WikiLeaks colleagues have turned on him, attacking the way he ran the site.

However, he retains many supporters and this month WikiLeaks was awarded a top Australian journalism prize, Walkley Awards, for its work in releasing the cables.

The suspected source of the cables, US soldier Bradley Manning, was arrested and has spent the last 18 months in a military prison.

WikiLeaks suffered a jolt when the site was forced to suspend releasing files in October after a funding blockade.

It resumed publication last week with the launch of a project on the global surveillance industry.