LONDON – A lawyer for Julian Assange said this week that the WikiLeaks founder was too sick to appear by video link for a court hearing related to a case that could see him extradited to the United States over computer hacking and espionage charges.

Assange's defense lawyer Gareth Peirce confirmed Thursday that the Australian national's health has deteriorated over the seven weeks that he has been held in Britain's Belmarsh prison, where he is serving a 50-week sentence for skipping bail.

On Wednesday, WikiLeaks said it had "grave concerns" about Assange's health. It said he had "dramatically lost weight" and that prison authorities moved him to a "health ward" in part because he was having trouble holding "normal conversations."

And on Friday, Nils Melzer, the United Nations special rapporteur on human rights, released a statement saying Assange was showing "symptoms typical for prolonged exposure to psychological torture, including extreme stress, chronic anxiety and intense psychological trauma." Melzer said these symptoms were likely the result of a years-long campaign against him by judges, political figures and some media.

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Assange is fighting extradition to the U.S. in connection with allegations he conspired with former Army intelligence analyst Chelsea Manning to leak classified military and diplomatic documents and committed a crime by publishing them on the Internet.

Thursday's hearing in London was a procedural one. The court case is expected to kick off in earnest around June 12 and last months. Prosecutors in Sweden have also recently re-opened a rape investigation into Assange, a move that complicates efforts to have him stand trail in the U.S. because Sweden also wants him extradited.

Assange was arrested in April 11 in London after Ecuador's government ended his seven years of self-imposed exile and expelled him from its London embassy.

He had sought refuge in the embassy to avoid extradition to Sweden over the sexual misconduct allegations. His legal team believed at the time that any extradition to Sweden would result in a subsequent extradition to the U.S., where they were concerned that he could face the death penalty. Assange's case has raised questions about the legal boundaries for publishing national security secrets.

More:Sweden prosecutors reopen Julian Assange rape probe, seek extradition