Wikileaks founder Julian Assange has recovered well after his release from jail last year, his wife told AFP ahead of the premiere of a documentary Wednesday that includes never-seen-before footage of the whistleblower.

Assange is at the Cannes Festival to promote the documentary by American filmmaker Eugene Jarecki, wearing a T-shirt with the names of killed Gaza children at a photo session on Tuesday. The 53-year-old former hacker is not talking to the media, however, with his wife Stella Assange saying, "He'll speak when he's ready."

"We live with incredible nature at our doorstep (in Australia). Julian's very outdoorsy. He always has been. He's really recovered physically and mentally," Stella, a Spanish-Swedish lawyer, told AFP.

Assange was released from a high-security British prison last June after a plea bargain with the US government over Wikileaks's work publishing top-secret military and diplomatic information.

He had spent five years behind bars fighting extradition from Britain and another seven holed up in the Ecuador embassy in London where he claimed political asylum.

Award-winning director Jarecki said his film, "The Six Billion Dollar Man", aimed to correct the record about Assange, whose methods and personality still make him a divisive figure.

"I think Julian Assange put himself in harm's way for the principle of informing the public about what corporations and governments around the world are doing in secret," Jarecki told AFP.

Anyone willing to trade years of their life for their principles, "I think you'd have to look at that person as having heroic qualities," he added.

The film includes personal videos handed over by Stella, who initially joined Wikileaks as a legal advisor and went on to have two children with Assange while he was living in the Ecuadorian embassy.

It also features testimony from people who helped spy on Assange, including a private security agent who said he installed bugs accessed by the American security services in the Ecuadorian embassy.

Former "Baywatch" actress and Assange's friend Pamela Anderson, fellow whistleblower Edward Snowden, and Australian human rights lawyer Jennifer Robinson also appear.

Jarecki pushed back on some of the criticism of Assange, notably that he endangered lives by publishing unredacted US documents with the names of people who spoke to American diplomats, including informants or human rights campaigners.

He also dismissed any links between Wikileaks and Russian intelligence services over the leak of Democratic Party emails ahead of the 2016 US presidential election which embarrassed Democrat candidate Hillary Clinton.

An investigation by US special counsel Robert Mueller, who probed alleged Russian interference in the 2016 vote, found evidence Russian military intelligence hacked the Democratic Party and passed the information to Wikileaks.

"Other than from the mouths of people in the Democratic Party, we've never found any evidence of any linkages between WikiLeaks and Russia," Jarecki claimed.

Ecuador's left-wing former president Rafael Correa, who offered Assange asylum in the Ecuadorian embassy in London, was to attend the film's red carpet premiere on Wednesday evening.

Jarecki was awarded the first ever Golden Globe for documentary at Cannes on Monday for his previous work, including his 2018 film about Elvis, "The King".

This year's festival is one of the most political for years, with hundreds of film industry figures including Hollywood heavyweights signing a letter condemning what they called "genocide" in Gaza.

It also denounced Israel's killing of Fatima Hassouna, a young Gaza photojournalist featured in the documentary "Put Your Soul in Your Hand and Walk", which premiered at Cannes last week.