Relatives and supporters of a Palestinian man held without charge by Israel said he was in critical condition in an Israeli hospital following a hunger strike of more than 70 days.

Maher al-Akhras, 49, began his hunger strike after he was arrested and placed into administrative detention in late July.

Administrative detention is a policy that allows Israel to detain suspects without filing charges, sometimes for months at a time with multiple extensions.

Al-Akhras’s wife, Taghreed, told The Associated Press that her husband has survived on water alone while he demands his release. Speaking from his room at Kaplan Medical Center in Rehovot, she said that al-Akhras has been hospitalised since September 6 and that he was too weak to speak or get up to go to the toilet.

“He lost half of his weight. He suffers spasms,” she said. “He has a constant strong headache and constant buzzing in the ears, fatigue, with no energy to talk to me.”

A medical official declined to provide details on the condition of al-Akhras, saying only that it was stable. The official, citing confidential medical information, spoke on condition of anonymity.

Israel’s Shin Bet security agency said al-Akhras was arrested on July 27 based on information that he is active in the Islamic Jihad armed group and was involved in “activities that endanger public safety”. It said he has been arrested five previous times for involvement in armed groups.

But al-Akhras’s wife said he is not an activist in any group, and only has campaigned for the rights of Palestinian prisoners held by Israel.

Al-Akhras’s lawyer, Ahlam Haddad, said he rejected an offer to be released at the end of his current administrative detention on November 26 and demands to be let go immediately.

His wife said al-Akhras knows his life is in danger. “He says this is the only way he can achieve justice,” she said.

The Palestinians and human rights groups say administrative detention violates the right to due process, since evidence is withheld from prisoners while they are held for lengthy periods without being charged, tried or convicted.

Qadura Fares, the head of the Palestinian Prisoners’ Club, said: “Administrative detention is a crime and should end. We hold Israel fully responsible for his life and call for his immediate release.”