Julian Assange has been moved to a medical wing in Belmarsh prison over concerns for his “significantly deteriorated” health, WikiLeaks has claimed.
The website said there are “grave concerns” for its founder as he has “dramatically lost weight” during his seven weeks in prison, and his condition has made it difficult for him to talk.
The group quoted defence lawyer Per Samuelson as saying after a meeting last week: “it was not possible to conduct a normal conversation with him”.
It added: “The decision of prison authorities to move him to the health ward speaks for itself.”
Last month, Mr Assange was arrested in London for breaching conditions of bail dating back to 2012.
He was pictured being dragged from the Ecuadorian embassy, where he had spent the last seven years on an asylum claim. Days later he was sentenced to 50 weeks in prison.
The 47-year-old had initially sought refuge with the South American nation for fears he would be extradited to Sweden to face charges of rape and sexual assault, and later to the US over the hacking of classified documents concerning Afghanistan and Iraq.
Swedish prosecutors dropped the case in 2017, but reopened it after Mr Assange’s arrest last month.
Last week, the US confirmed 17 new charges against the WikiLeaks founder, including allegations of espionage.
A formal hearing on the US extradition request is set to take place at Westminster Magistrates’ Court later today.
In a brief statement, WikiLeaks’ editor-in-chief Kristinn Hrafnsson said Mr Assange’s case had become a “black stain on history”.
He said: “Julian’s case is of major historic significance. It will be remembered as the worst attack on press freedom in our lifetime.”