WikiLeaks founder Julian Assange has won his fight to avoid extradition to the United States.

District Judge Vanessa Baraitser said at the Old Bailey on Monday that, due to the real risk of suicide, the 49-year-old should not be extradited by “reason of mental health”.

Assange, who sat in the dock of Court 2 in a blue suit and wearing a green face mask below his nose, closed his eyes as the judge read out her ruling.

He is not expected to be freed from high-security Belmarsh Prison immediately as the US government are likely to appeal, but he can make a fresh application for bail.

Assange is wanted to face an 18-count indictment, alleging a plot to hack computers and a conspiracy to obtain and disclose national defence information.

The case followed WikiLeaks’ publication of hundreds of thousands of leaked documents in 2010 and 2011 relating to the Afghanistan and Iraq wars, as well as diplomatic cables.

Prosecutors say Assange helped US defence analyst Chelsea Manning breach the Espionage Act in unlawfully obtaining material, was complicit in hacking by others, and published classified information that put the lives of US informants in danger.

Assange denies plotting with Manning to crack an encrypted password on US Department of Defence computers and says there is no evidence that anyone’s safety was put at risk.

His legal team argued that the prosecution is political and said Assange, who has been diagnosed with Asperger’s syndrome and severe depression, is a high suicide risk if he is extradited.

In her judgment, Judge Baraitser referred to evidence of Assange’s mental state.

She said that “facing conditions of near total isolation” in US custody, she was satisfied that authorities there would not be able to prevent Assange from “finding a way to commit suicide”.

Assange’s lawyers had said he faced up to 175 years in jail if convicted, although the US government said the sentence was more likely to be between four and six years.

Assange wiped his brow after the decision was announced while his fiancee, Stella Moris, with whom he has two young sons, wept.

She was embraced by WikiLeaks editor-in-chief Kristinn Hrafnsson, who sat next to her in court as the judgment was delivered.

The prosecution have given notice of appealing over the decision and have 14 days to lodge their grounds.

In her ruling, the judge rejected the defence arguments of freedom of speech and that the prosecution was politically motivated.

She said: “If the allegations are proved then the agreement with Ms Manning and other groups of computer hackers took him outside any role of investigative journalism.

“He was acting to further the overall objective of WikiLeaks to obtain protected information by hacking, if necessary.”

The judge said Assange’s dealings with Ms Manning “went beyond the mere encouragement of a journalist”.

She said Assange was “well aware” of the danger to informants by disclosing unredacted names in leaked documents.

If Assange’s conduct was proved it would amount to offences in this jurisdiction and he would not be protected by freedom of speech, she said.

The judge added: “Free speech rights don’t provide unfettered discretion for some, like Mr Assange, to decide the fate of others.”

On the claim that the charges were politically motivated, she said: “There was insufficient evidence to find the prosecutors responsible for bringing these charges were pressurised by the Trump administration.

“There is little or no evidence to indicate hostility by President Trump to Mr Assange or WikiLeaks.”

She added: “I accepted Mr Assange has political opinions. However, I was satisfied that the federal prosecutors who acted to bring these charges did so in good faith.”