The organisation, famous for releasing classified information on war crimes committed by US troops in the Middle East, released a statement following Assage’s arrest.
It said: “WikiLeaks has grave concerns about the state of health of our publisher, Julian Assange, who has been moved to the health ward of Belmarsh Prison.
“Mr Assange’s health had already deteriorated after seven years inside the Ecuadorian embassy, under conditions that were incompatible with basic human rights.
WikiLeaks’s statement continued: “During the seven weeks in Blemish his health has continued to deteriorate and he has dramatically lost weight.
“The decision of prison authorities to move him to the health ward speaks for itself.”
Assange, 47, was apprehended by cops after he finally left the Ecuadorian embassy in London in April.
It comes just hours before Assange is due to appear in court for a hearing into possible extradition to the US where he would face hacking and espionage charges.
He fled to the London-based embassy after Swedish authorities ordered his arrest following a rape accusation that was made against him.
“WikiLeaks has grave concerns about the state of health of our publisher, Julian Assange”
Assange denies the charge.
Sweden has since filed a request for Assange to be extradited to the Scandinavian country.
Daily Star Online has attempted to approach the Ministry of Justice for comment.