A Palestinian on hunger strike since December 18 appealed his detention without charge on Thursday in a special court session held in an Israeli hospital, his lawyer said.

Khader Adnan has been on hunger strike for 54 days, longer than any Palestinian prisoner before him according to Palestinian officials, protesting what he calls his unjust detention and mistreatment by Israeli authorities.

A military court early this month ordered he be held in administrative detention for four months, though with his condition frail and worsening, he has been held mostly in a string of Israeli hospitals since early January.

"We asked during the hearing for the cancellation of the administrative detention order and the immediate release of Khader Adnan," lawyer Jawad Bulus said.

"They investigated him and they haven't proved anything against him."

The court session was originally scheduled to take place in Ofer military court near the West Bank city of Ramallah, but Adnan's condition meant moving him, even by ambulance, would have endangered his life, Bulus said.

The court sought to postpone the hearing, but Adnan insisted it go ahead, instead appearing before the military judge in a room at the Ziv hospital in the northern Israeli city of Safed.

"Khader's voice was frail and weak. He testified about the harsh conditions of his detention and the restrictions that have been placed on him on hospital now," Bulus said.

He said the court issued no decision and was not expected to rule before Sunday on Adnan's appeal.

"The prosecutors presented the documents that they say show the need for his continuing detention, and we warned them that if he is not released we will go to the Israeli High Court," Bulus said.

Adnan is being held shackled to a hospital bed under guard, and doctors from Israeli group Physicians for Human Rights-Israel told AFP they have been refused permission to meet with him privately.

Adnan, who was arrested near the northern West Bank city of Jenin, had served as a spokesperson for Islamic Jihad, but Israel has not charged him formally or revealed any evidence against him.

Under Israeli military law, a court can order an individual be held for up to six months at a time without charge, though the order can be appealed.

Each renewal must be approved in a new court session, but the renewals theoretically continue indefinitely.

Bulus said neither he nor Adnan will be given access to the documents submitted by the prosecution because they are deemed to contain sensitive security information.

Adnan, who was arrested on December 17, says Israel has no evidence against him, and accuses his interrogators of mistreating him, saying they made crude, sexual comments about his wife and pulled his beard until his hair came out.

He began refusing food the day after arrest and started refusing water on January 31, though doctors from Physicians for Human Rights-Israel said he was consuming some water, without nutrients or salt.

The Palestinian Prisoners' Club, which monitors the wellbeing of thousands of Palestinians held in Israeli prisons, says Adnan has now been on hunger strike longer than any Palestinian prisoner before him.

Qaddura Fares, chairman of the Club, said their records show six Palestinian prisoners have died on hunger strike in Israeli prisons.