Lawyers for the WikiLeaks founder Julian Assange asked a British judge on Friday to drop a 2012 arrest warrant, a request that if granted could allow Mr. Assange to leave the Ecuadorean Embassy in London, where he has been living for five and a half years, and fly to Ecuador, which has granted him citizenship.

Mr. Assange, a 46-year-old native of Australia, was ordered extradited to Sweden in February 2011 to face a charge of rape, which he denied. After his challenges to the extradition order were refused, he skipped bail and fled to the embassy in June 2012. He was granted asylum two months later and has remained at the embassy, in the wealthy Knightsbridge district of West London, ever since.

Mr. Assange feared that Sweden would turn him over to the United States to face prosecution over WikiLeaks’ publication of troves of classified government documents on the wars in Afghanistan and Iraq, classified diplomatic cables and electronic hacking by the C.I.A., among other subjects.

Sweden dropped the rape inquiry in May, and withdrew the European arrest warrant it had requested. But the British authorities insist that Mr. Assange could still be arrested, for bail violations, if he leaves the embassy.