A Palestinian prisoner refusing food for months over his detention ended his hunger strike Tuesday after Israel committed to his eventual release, his lawyer told AFP.

Hisham Abu Hawash, a 40-year-old member of the Islamic Jihad militant movement, began refusing food in August to protest Israel holding him without charges or trial.

The married father of five from Dura, in the south of the Israeli-occupied West Bank, is being held under administrative detention -- a practice of arresting suspects for renewable six-month terms without allowing them to view the charges or evidence against them.

Under an agreement proposed to Abu Hawash, his detention will not be extended beyond February 26 in return for his ending his fast.

His lawyer, Jawad Boulos, said Abu Hawash accepted the deal.

"He agreed and ended his hunger strike just 10 minutes ago, he had some tea, and everything is okay," Boulos told AFP late Tuesday.

The International Committee of the Red Cross, whose medical teams visited Abu Hawash over the weekend, said he was in "critical condition" after fasting for some 140 days, warning of "potentially irreversible health consequences and possible tragic loss of life".

An Israeli security source noted February 26 would be the end of his current six-month detention period, meaning it wasn't shortened, but at the same time, the deal meant Israel would not renew it.

The deal came after a campaign that drew support from Palestinians, ranging from Fatah that rules the West Bank, to militant factions in Gaza threatening revenge on Israel if Abu Hawash died.

Palestinian prime minister Mohammad Shtayyeh said the government was following the case and acting on the behalf of Abu Hawash.

Hamas, the militant Islamist movement that rules the Gaza Strip, warned the issue was a "red line" for Palestinians.

Islamic Jihad, the second largest militant group in Gaza, said it held "the Israeli occupation fully responsible for the deteriorating health" of Abu Hawash, threatening revenge if he died.

Demonstrations in his support were held in recent days in the West Bank and Gaza. 

An Israeli security source described Abu Hawash as "an Islamic Jihad operative, who was arrested due to involvement in terror activity".

Israel says the protocol prevents crimes while authorities continue to gather evidence, though Palestinians say it denies them their rights.