Julian Assange could die in prison without urgent medical treatment, according to an open letter signed by more than 60 doctors who say the WikiLeaks founder is suffering from physical and psychological problems, including depression, reports Sky News.
The UK, European, Australian and Sri Lankan doctors expressed "serious concerns" about Assange's fitness to stand trial in the letter addressed to Home Secretary Priti Patel.
Assange, 48, is being held in Belmarsh prison, southeast London, ahead of a hearing in February to fight extradition to the US, where he faces 18 charges, including conspiring to hack into a classified Pentagon computer.
The doctors are calling for Assange to be transferred to a university teaching hospital, where he can be assessed and treated by a medical team.
The letter, which has been distributed by WikiLeaks, says: "From a medical point of view, on the evidence currently available, we have serious concerns about Mr Assange's fitness to stand trial in February 2020.
"Most importantly, it is our opinion that Mr Assange requires urgent expert medical assessment of both his physical and psychological state of health.
"Any medical treatment indicated should be administered in a properly equipped and expertly staffed university teaching hospital (tertiary care).
"Were such urgent assessment and treatment not to take place, we have real concerns, on the evidence currently available, that Mr Assange could die in prison.
"The medical situation is thereby urgent. There is no time to lose."
Last week, WikiLeaks welcomed the decision by the Swedish authorities to drop a rape investigation into Assange.
Assange, from Australia, was jailed for 50 weeks in May for breaching his bail conditions after going into hiding in the Ecuadorian embassy in London for seven years to avoid extradition to Sweden over the sex offence allegations, which he has always denied.
He has been in custody since he was removed from the building in April after his asylum status was withdrawn by the South American country's president.