LONDON — Julian Assange’s lawyers on Tuesday began their final UK legal challenge to stop the WikiLeaks founder from being sent to the United States to face spying charges.

According to a news report from The Associated Press, Judge Victoria Sharp said Assange was granted permission to come from Belmarsh Prison, where he has been held for five years, but had chosen not to attend court. His lawyer, Edward Fitzgerald, said the 52-year-old Australian was unwell.

AP News says Assange has been fighting extradition for more than a decade, including seven years in self-exile in the Ecuadorian Embassy in London and the last five years in the high-security prison.

He has been indicted on 17 charges of espionage and one charge of computer misuse over his website’s publication of classified US documents. US prosecutors say Assange helped US Army intelligence analyst Chelsea Manning steal diplomatic cables and military files that WikiLeaks later published, putting lives at risk.

Assange’s attorneys are asking judges to grant a new appeal hearing. According to the report from AP News, if the judges rule against Assange, he can ask the European Court of Human Rights to block his extradition even as several of his arguments against extradition have already been rejected by British courts.