A British judge has rejected the United States’ request to extradite WikiLeaks founder Julian Assange to face espionage charges, saying it would be “oppressive” because of his mental health.

District Judge Vanessa Baraitser said on Monday that Assange was likely to commit suicide if sent to the US.

The US government said it would appeal the decision.

US prosecutors have indicted Assange on 17 espionage charges and one charge of computer misuse over WikiLeaks’ publication of leaked military and diplomatic documents a decade ago. The charges carry a maximum sentence of 175 years in prison.

Lawyers for the 49-year-old Australian argue that he was acting as a journalist and is entitled to First Amendment protections of freedom of speech for publishing leaked documents that exposed US military wrongdoing in Iraq and Afghanistan.

The judge rejected claims by the defence that Assange was protected by free-speech guarantees, saying his “conduct, if proved, would therefore amount to offences in this jurisdiction that would not be protected by his right to freedom of speech”.

But she said Assange suffered from clinical depression that would be exacerbated by the isolation he would likely face in US prison.

The judge said Assange had the “intellect and determination” to circumvent any suicide prevention measures the authorities could take.

Judge Baraitser had last year told London’s Old Bailey Court at the conclusion of Assange's extradition hearings that she would deliver her verdict on Jan 4.

Assange’s legal travails in Britain date to 2010, when he began fighting an attempt to extradite him to Sweden to answer questions about allegations of sexual assault, which were later dropped.

In June 2012, he sought refuge in the Ecuadorean embassy where he remained for seven years. He was dragged out in April last year and served a jail term for violating bail, but has remained in prison after the US extradition process began.

Those hearings began in February for a week and were due to resume in May, but the coronavirus lockdown meant they were then postponed until September.