WikiLeaks founder Julian Assange was too ill on Thursday to appear via video link from a British prison in a hearing on an extradition request from the United States, his lawyer said, reports Reuters.

The United States is seeking the extradition of Assange, 47, who was dragged from the Ecuadorean embassy in London on April 11. He faces a total of 18 U.S. criminal counts and decades in prison if convicted.

“He’s in fact far from well,” Assange’s lawyer, Gareth Peirce told Westminster Magistrates’ Court.

WikiLeaks said it had grave concerns about Assange’s health.

The next hearing on the extradition request was set for June 12.