Pamela Anderson says WikiLeaks founder Julian Assange has been subjected to "traumatic psychological torture", as she urged his home country Australia to stop him being extradited to the US.

The former Baywatch star - one of Assange's most high-profile supporters - has written letters to Australian prime minister Scott Morrison, foreign affairs minister Marise Payne, US President Donald Trump and first lady Melania Trump.

Anderson tweeted that Assange was "hanging on like a super hero" in Belmarsh prison, where he was sent earlier this year after spending seven years in the Ecuadorean embassy in London to avoid extradition.

The actress visited Assange in jail earlier this year and is planning another visit this month.

She said she was "extremely distressed at the thought of his declining state" and that her heart broke for him.

She said: "I am hopeful that he will even be able to recover from the traumatic psychological torture that he has been systematically subjected to, as declared by the UN special rapporteur on torture Mr Nils Melzer.

"Julian must be allowed to heal in a natural environment that he has been deprived of for so long. The natural beauty of his native country Australia, surrounded by his loving family, is what he urgently needs."

Anderson said the whistleblower was "strong, focused and willing to sacrifice even his life for all of us" but that she could not allow that to happen.

Urging Australians to support him, she said: "When I visit Julian in a few weeks I am very much looking forward to be able to convey to him that the tide is shifting.

"Australian citizens... together with Australian parliamentarians are now standing up and together to declare they want the Australian Government to 'Bring Assange Home'.

"I know this will be a crucial piece of great news that will lift Julian's spirits.

"You cannot let him be extradited. You must protect him and have his back. It's a death trap.

"It will go down in the history books as the weakest decision ever made by Australia."

The star, who is also planning to speak to Mr Trump, said it was "unconscionable that a citizen of Australia or any other western democracy may be extradited to the USA", adding it was "a potential death sentence for simply publishing the facts".

Anderson also claimed that Assange had been "unfairly and inappropriately disadvantaged in the mounting of his defence".

She said: "I make a heartfelt personal plea to every parliamentarian that is charged with the responsibility to uphold the protection of the citizens of Australia to now stand and protect Julian Assange by initiating contact with your counterparts in the USA and Britain and demand no extradition and allow Julian to walk free as a valuable teacher and Citizen of Australia."

Assange was jailed for 50 weeks in May for breaching his bail conditions after going into hiding in the Ecuadorian embassy in London for nearly seven years to avoid extradition to Sweden over sex offence allegations.

He faces 18 charges in the US, including allegations that he conspired to break into a Pentagon computer and worked with former US army intelligence analyst Chelsea Manning to leak hundreds of thousands of classified documents.

PA Media