Dozens of doctors have signed an open letter warning that Julian Assange’s health has declined so far that the WikiLeaks founder could die inside the top-security British jail where he’s being held. Assange is being detained in Belmarsh prison, where he’s fighting a U.S. bid to extradite him from the U.K. on charges filed under the Espionage Act. In the letter addressed to Britain’s home secretary, Priti Patel, the group of doctors said Assange should be moved from prison to a university teaching hospital. They said their diagnosis is based on “harrowing eyewitness accounts” of his Oct. 21 court appearance in London. “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,” they wrote. The doctors are from the U.S., Australia, U.K., Sweden, Italy, Germany, Sri Lanka, and Poland.