Khader Adnan, 44, from Arraba in Jenin, stopped taking food in protest at his arrest and detention by Israeli authorities.
The Palestinian Prisoners Club said Israel’s refusal to respond to his demand was a “death sentence” and that his condition had become “dangerous.”
Despite Adnan’s medical emergency, the Israeli authorities have refused to end his detention, allow his family to visit, or transfer him permanently to a civil hospital, the club said.
Every time he is transferred to a hospital, he is returned under the pretext that he refused medical support, it added.
During a meeting with his lawyer on Tuesday in Ramla prison, Adnan lost consciousness and later had no memory of what happened to him. The prison administration told his lawyer that it would transfer him to a hospital.
During a video court hearing on Sunday, Adnan, a member of the Islamic Jihad group, passed out several times and suffered severe convulsions.
The court rejected his lawyer’s request that he be released on bail.
Adnan has been detained since Feb. 5, the day he announced his hunger strike. The Israeli authorities filed an indictment against him which was swiftly rejected by Adnan.
His wife said in press statements on Tuesday that no information about Adnan’s condition was made available after he was transferred to a hospital.
Prison authorities postponed a scheduled visit by his lawyer at noon on Tuesday.
Jamil Alayan, an Islamic Jihad leader, said: “We will not allow the Israeli occupation to unilaterally kill the prisoner, Adnan,” adding that what was happening amounted to an “execution.”
Shawan Jabarin, director of the Al-Haq Institution for Human Rights in Ramallah, told Arab News that Israeli authorities refused to release Adnan on bail because they did not deal with the Palestinians according to the law.
“There are no fair trial procedures in the Israeli military judiciary when it comes to the Palestinians,” Jabarin said.
Palestinians in Gaza held a sit-in to express solidarity with the prisoner.
A number of the prisoners’ families staged a protest in front of the Red Cross office in the occupied West Bank town of Tulkarm in support of those incarcerated in Israeli prisons, including Adnan, and against the Israeli policy of administrative detention and deliberate medical negligence.
According to the Prisoners Club, 4,900 prisoners, including 31 women, 160 children, more than 1,000 administrative detainees and 19 journalists have been detained by Israel. Hundreds of sick and older prisoners are being kept in harsh conditions, it said.
Almost 400 prisoners have been held in detention for more than 20 years, it said.
The number of prisoners is increasing daily and has risen by more than 2,300 since the beginning of the year, while the number of Palestinians arrested since the Israeli occupation of the Palestinian territories now exceeds 1 million.
Palestinian prisoners are facing worsening conditions since the arrival of Israeli National Security Minister Itamar Ben-Gvir, who has pledged unprecedented punitive measures against them.