High-level contacts between Israeli and Palestinian officials are underway over the fate of a Palestinian hunger striker said to be close to death, a source told AFP on Sunday.

A Palestinian source, who spoke on condition of anonymity, said both sides were seeking to avoid a situation in which Khader Adnan, on hunger strike since December 18, dies in Israeli custody.

"From a medical point of view, between 57 and 75 days on hunger strike is when you start to have internal organ death, so Adnan has entered the period of extreme danger to his life," the source said.

"Therefore, contacts are underway between the two sides to find a solution that would avoid Adnan's death."

The Palestinian Authority has formally requested his release, the source added.

Adnan has been on hunger strike longer than any Palestinian prisoner before him, and the Israeli government has faced increasing pressure, including from international rights groups to charge or release him.

Palestinian officials have warned of massive demonstrations across the West Bank and Gaza if Adnan dies in Israeli custody.

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.

A one-time spokesman for Islamic Jihad, he has not been charged with anything and is being held under a four-month administrative detention order.

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

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

Adnan appealed his administrative detention last Thursday in a special military court session convened in the Israeli hospital where he is currently being held.

His lawyer was told a decision on the appeal would be issued on Sunday, but by Sunday afternoon it was unclear when a ruling would be made.

The Israeli military said it had no comment or information on the case.

The Palestinian source said one proposal being discussed with Israeli officials would see the four-month order against Adnan reduced to two months, with Israel releasing him on or around February 17, two months after his arrest.

But Israeli officials are said to be reluctant to release Adnan, fearing a wave of similar hunger strikes by other Palestinian prisoners in Israeli jails.

On Sunday, Palestinian officials said Palestinians in prisons throughout Israel were staging a one-day hunger strike in solidarity with Adnan.