Julian Assange's fiancée accuses US of wanting to lock him up indefinitely

Stella Moris says extradition proposals would see him incarcerated for the rest of his life

Julian Assange is in custody in the UK pending an appeal by the US over his extradition. (AP Photo / Frank Augstein, File)

Julian Assange's fiancée has rejected extradition proposals put forward by the US, saying they would effectively see her partner locked up indefinitely.

Stella Moris hit out at the proposals after the US was granted leave to appeal a decision by the UK's High Court in London not to extradite him on mental health grounds.

The US is seeking his extradition so he can stand trial on espionage and hacking-related charges over WikiLeaks' publication of hundreds of thousands of US military and diplomatic documents.

This week the US gave the UK assurances he would not be held under the strictest maximum-security conditions if extradited and said he would be allowed to serve any jail time in his native Australia.

Ms Moris said the US assurances were "laughable".

"Julian won his case in January and the US is now appealing that victory", she said.

"It is telling the UK that it will not place him under certain conditions. Any so-called undertakings by the US are laughable because the US should not be putting journalists in prison in the first place. The undertakings are not worth the paper they are written on."

She said assurances he would not be placed in a maximum security prison in Florida do not mean that he might not be placed in one somewhere else.

"There are multiple prisons they can chose from", she said.

She also dismissed their claims that he might be allowed to serve his sentence in Australia, saying that prisoner transfers only take place after all appeals processes have been exhausted and that this would take decades.

Mr Assange has now spent nine years in jail or self-incarceration in Britain.

He has been detained by the British authorities pending the appeal by the US.

In January, Judge Vanessa Baraitser ruled that Mr Assange was suffering from mental health problems that would raise the risk of suicide if he were sent to the US for trial.