A British court could give a final decision on Monday on whether WikiLeaks' founder Julian Assange should be extradited to the United States over the mass leak of secret US documents, the culmination of 13 years of legal battles and detentions.

Two judges at the High Court in London are set to rule on whether the court is satisfied by US assurances that Assange, 52, would not face the death penalty and could rely on the First Amendment right to free speech if he faced a US trial for spying.

Assange's legal team say he could be on a plane across the Atlantic within 24 hours of the decision, could be released from jail, or his case could yet again be bogged down in months of legal battles.

"I have the sense that anything could happen at this stage," his wife Stella said last week. "Julian could be extradited, or he could be freed."

She said her husband hoped to be in court for the crucial hearing.

WikiLeaks released hundreds of thousands of classified US military documents on Washington's wars in Afghanistan and Iraq - the largest security breaches of their kind in US military history - along with swathes of diplomatic cables

In April 2010 it published a classified video showing a 2007 US helicopter attack that killed a dozen people in the Iraqi capital, Baghdad, including two Reuters news staff.

The US authorities want to put the Australian-born Assange on trial over 18 charges, nearly all under the Espionage Act, saying his actions with WikiLeaks were reckless, damaged national security, and endangered the lives of agents.

His many global supporters call the prosecution a travesty, an assault on journalism and free speech, and revenge for causing embarrassment. Calls for the case to be dropped have ranged from human rights groups and some media bodies, to Australian Prime Minister Anthony Albanese and other political leaders.

Assange was first arrested in Britain in 2010 on a Swedish warrant over sex crime allegations that were later dropped. Since then he has been variously under house arrest, holed up in Ecuador's embassy in London for seven years, and held since 2019 in Belmarsh top security jail, latterly while he waited a ruling on his extradition.