WikiLeaks founder Julian Assange has reportedly been moved to the hospital wing of HMP Belmarsh following "dramatic" weight loss and health complications

Assange is due to appear in court today for a hearing on his extradition to the United States to face espionage charges.

In a statement last night, the organisation 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 significantly deteriorated after seven years inside the Ecuadorian Embassy, under conditions that were incompatible with basic human rights.

"During the seven weeks in Belmarsh his health has continued to deteriorate and he has dramatically lost weight.

"The decision of prison authorities to move him to the ward speaks for itself."

Assange was arrested in London in April after being dragged out of the Ecuadorean Embassy.

He had been holed up in the sovereign building for seven years to avoid capture.

The United States is seeking his extradition from the UK - where he's been jailed for 50 weeks for breaching bail.

The 47-year-old was booted out of the embassy - where he hid to avoid being sent to Sweden to face rape allegations.