London, UK - The High Court in London Tuesday will begin hearing WikiLeaks founder Julian Assange's final UK appeal against extradition to the United States to face trial over publishing secret military and diplomatic files.

Washington wants the 52-year-old Australian citizen extradited after he was charged there multiple times between 2018 and 2020 in connection with WikiLeaks' 2010 publication of files relating to the US-led wars in Iraq and Afghanistan.

The long-running legal saga in Britain's courts is now nearing a conclusion, after Assange lost successive rulings in recent years.

If this week's two-day bid to appeal – set to begin at 10:30 AM Tuesday – is successful, he will have another chance to argue his case in a London court, with a date set for a full hearing.

If he loses, Assange will have exhausted all UK appeals and will enter the extradition process, although his team have indicated they will appeal to European courts.

His wife Stella Assange has said he will ask the European Court of Human Rights to temporarily halt the extradition if needed, warning he would die if sent to the United States.

"Tomorrow and the day after will determine whether he lives or dies essentially, and he's physically and mentally obviously in a very difficult place," she told BBC radio on Monday.

US President Joe Biden has faced sustained pressure, both domestically and internationally, to drop the 18-count indictment Assange faces in federal court in Virginia, which was filed under his predecessor Donald Trump.

Major media organizations, press freedom advocates, and the Australian parliament are among those decrying the prosecution under the 1917 Espionage Act, which has never been used before over publishing classified information.

But Washington has maintained the case, which alleges Assange and others at WikiLeaks recruited and agreed with hackers to conduct "one of the largest compromises of classified information" in US history.

Assange, detained in the high-security Belmarsh Prison in southeast London since April 2019, was arrested after spending seven years holed up in Ecuador's London embassy. He fled there 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 United States vowed to not 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."

In March 2022, the UK's 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, but Assange is now seeking permission to review that decision and the 2021 appeal ruling.

If convicted in the United States, he faces a maximum sentence of 175 years in jail.

Kristinn Hrafnsson, WikiLeaks' editor-in-chief, told reporters last week that caveats included within the US promises meant they were "not worth the paper they are written on."

On the same day, Australia's Prime Minister Anthony Albanese denounced the years-long legal pursuit of Assange, saying "enough is enough."

It followed the country's parliament passing a motion calling for an end to his prosecution.

Assange has two children with his wife Stella, a lawyer whom he met when she worked on his case.