Julian Assange has had a stroke in Belmarsh Prison, his fiancee Stella Moris revealed last night.

The WikiLeaks publisher, 50, who is being held on remand in the maximum-security jail while fighting extradition to America, was left with a drooping right eyelid, memory problems and signs of neurological damage.

He believes the mini-stroke was triggered by the stress of the ongoing US court action against him, and an overall decline in his health as he faces his third Christmas behind bars.

It happened at the time of a High Court appearance via video link from Belmarsh in October.

A ‘transient ischaemic attack’ – the interruption of the blood supply to the brain – can be a warning sign of a full stroke. Assange has since had an MRI scan and is now taking anti-stroke medication.

Ms Moris, 38, a lawyer, said: ‘Julian is struggling and I fear this mini-stroke could be the precursor to a more major attack. It compounds our fears about his ability to survive the longer this long legal battle goes on. 

‘It urgently needs to be resolved. Look at animals trapped in cages in a zoo. It cuts their life short. That’s what’s happening to Julian. The never-ending court cases are extremely stressful mentally.’ 

She said he was kept in his cell for long periods and was ‘short of fresh air and sunlight, an adequate diet and the stimulus he needs’.

Assange faced a major legal setback on Friday when the High Court overturned a judgment made this year preventing extradition to the US to face charges under the US Espionage Act.

His lawyers successfully argued he would be kept in conditions in the US that could lead to a serious risk of suicide. The High Court reversed the earlier ruling after the US government offered assurances about his potential imprisonment.

But Ms Moris said: ‘I believe this constant chess game, battle after battle, the extreme stress, is what caused Julian’s stroke on October 27. 

He was feeling really unwell, far too ill to follow the hearing, and he was excused by the judge but could not leave the prison video room.

‘It must have been horrendous hearing a High Court appeal in which you can’t participate, which is discussing your mental health and your risk of suicide and in which the US is arguing you are making it all up. 

‘He had to sit through all this when he should have been excused. He was in a truly terrible state. His eyes were out of synch, his right eyelid would not close, his memory was blurry.’

Assange was examined by a doctor, who found a delayed pupil response when a light was shone into one eye – a sign of potential nerve damage.

Ms Moris and Assange have two sons, Gabriel, four, and Max, two, and have been engaged for five years. She said he had ‘more or less’ recovered – but she fears the attack shows his health is failing.

She visited him for around an hour yesterday, taking the children to see him in a prison hall shared by dozens of inmates and their loved ones.

She said Assange was distressed about being kept from his family, adding: ‘He finds the prospect of a third Christmas in prison difficult.’

The US wants Assange to face allegations of conspiracy to obtain and disclose national defence information after Wikileaks published hundreds of thousands of leaked documents relating to the Afghanistan and Iraq wars.

He sheltered at the Ecuadorian Embassy in London in 2012 because he feared extradition, staying for seven years until he was forcibly removed and sent to Belmarsh in 2019. 

He has until December 23 to appeal against last week’s judgment, and could face many months – potentially years – on remand in the UK.

Ms Moris said: ‘It remains an outrage that someone who is not serving a prison sentence should be held in prison for years on end. 

‘Julian is not a threat to anyone and it is a complete disregard to his individual liberty and our right to a family life.

‘The US plays dirty every step of the way – it’s a war of attrition. We can see from the fact that he has suffered a mini-stroke this is having a dangerous impact on him.’

A spokesman for the Ministry of Justice said last night he would not comment on an individual prisoner.