Supporters of Assange and WikiLeaks demonstrated outside the High Court in London in February
Supporters of Assange and WikiLeaks demonstrated outside the High Court in London in February AFP

Two UK judges delayed a decision Tuesday on whether to grant WikiLeaks founder Julian Assange a last-ditch appeal against extradition to the United States, giving Washington three weeks to provide further "assurances" in the case.

The US wants the 52-year-old Australian citizen to stand trial there for WikiLeaks' publication of hundreds of thousands of secret military and diplomatic files in 2010 relating to the wars in Iraq and Afghanistan.

Attempting to halt the process, Assange had suffered a string of court losses in the long-running legal saga, which his supporters see as a battle for media freedom.

But following two days of evidence last month, the judges in London said he had "a real prospect of success" on three of his nine grounds of appeal.

Victoria Sharp and Jeremy Johnson gave Washington three weeks to allay concerns that he will be prejudiced at trial because he is not an American citizen and that he could face the death penalty if convicted.

"Before making a final decision on the application for leave to appeal, we will give the respondent an opportunity to give assurances," the pair wrote in their 66-page ruling.

"If assurances are not given then we will grant leave to appeal without a further hearing.

"If assurances are given then we will give the parties an opportunity to make further submissions before we make a final decision."

Tuesday's ruling, which was released online, means Assange will remain at the high-security prison in southeast London where has been held since 2019.

He did not attend February's hearing either in person or remotely due to illness.

If he is eventually granted another appeal, the case will be heard in a London court.

But if the judges are swayed by the US's reassurances, Assange will have exhausted all UK appeals and be extradited.

His team has previously indicated, however, that they will ask the European courts to intervene and that they would be given 14 days to do so.

Assange's wife Stella, who has led the campaign to block his extradition, called the latest decision "astounding".

"What the courts have done is to invite political intervention from the United States, to send a letter saying 'it is all OK'," she told reporters outside the court.

Campaign groups including Amnesty International and Reporters Without Borders also called for Assange's release.

"The US must stop its politically motivated prosecution of Assange, which puts Assange and media freedom at risk worldwide," said Simon Crowther, Amnesty's legal adviser.

The US indicted Assange multiple times between 2018 and 2020 but US President Joe Biden has faced persistent domestic and international pressure to drop the case filed under his predecessor Donald Trump.

Major media organisations, press freedom advocates and the Australian parliament have all denounced the prosecution under the 1917 Espionage Act, which has never been used over the publishing of classified information.

Washington alleges that Assange and others at WikiLeaks recruited and agreed with hackers to conduct "one of the largest compromises of classified information" in US history.

During last month's hearing, lawyers for the US government defended the case on various legal grounds.

Lawyers for Assange submitted that the charges were "political" and that he was being prosecuted "for engaging in ordinary journalistic practice of obtaining and publishing classified information".

They also argued that the decades-long prison sentence he faces if convicted was "disproportionate".

Before going to prison, Assange spent seven years holed up in Ecuador's London embassy to avoid extradition to Sweden, where he faced accusations of sexual assault which were later dropped.

The High Court had blocked his extradition, but then reversed the decision on appeal in 2021 after the US vowed not to imprison him in its most extreme prison, "ADX Florence".

It also pledged not to subject him to the harsh regime known as "Special Administrative Measures", and to allow him to eventually serve out his sentence in Australia.

In March 2022, the UK Supreme Court refused permission to appeal, arguing Assange failed to "raise an arguable point of law".

Months later, ex-interior minister Priti Patel formally signed off on his extradition.

Assange is seeking permission to review that decision and the 2021 appeal ruling.

Assange's wife, Stella, says they will take the case to the European Court of Human Rights if necessary
Assange's wife, Stella, says they will take the case to the European Court of Human Rights if necessary AFP
The hearing is likely Assange's last chance to fight extradition in Britain's courts after a years-long battle.
The hearing is likely Assange's last chance to fight extradition in Britain's courts after a years-long battle. AFP
Washington indicted the WikiLeaks founder over its publication of hundreds of thousands of secret military and diplomatic files
Washington indicted the WikiLeaks founder over its publication of hundreds of thousands of secret military and diplomatic files AFP