Assange 'not well', US extradition hearing moved to June

Britain's review of a US request to extradite WikiLeaks founder Julian Assange on espionage charges has been moved to June, with his lawyer telling court on Thursday the whistleblower is in poor health.

The United States has slapped 18 charges against the 47-year-old Australian, who had been hiding in London's Ecuadorian embassy for seven years until his arrest on April 12.

Sweden has since reopened a 2010 rape investigation against Assange and could file its own extradition request.

The Westminster Magistrates Court in London held a brief hearing on Thursday at which it moved the US case to June 12.

Chief magistrate Emma Arbuthnot referred to Assange as "not very well", with the next hearing possibly taking place at the Belmarsh prison where he is serving a separate 50-week sentence for skipping bail.

"It may be more convenient for everyone if it's there," Arbuthnot said.

WikiLeaks expressed "grave concerns" Wednesday over Assange's condition.

The websites, which published a trove of classified State Department and Pentagon material about US operations in Afghanistan and Iraq, said Assange has been moved to the prison's health ward.

"During the seven weeks in Belmarsh his health has continued to deteriorate and he has dramatically lost weight," WikiLeaks said in a statement.

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