Hunger-striking detainees affiliated to Fatah said Thursday they are refusing medicine as well as food and water until Israel responds to their demands.
A representative for Fatah prisoners informed party officials in Gaza that detainees were determined to achieve the goals of the strike, which include family visits, access to education and an end to solitary confinement.
Detainees urged the international community to intervene to save prisoners' lives.
Thousands of Palestinians are on hunger strike in Israeli jails to demand an end to Israeli policies including detaining Palestinians without charge, solitary confinement and restricting access to education.
On Saturday, representative for Fatah prisoners Jamal al-Rjoob said detainees affiliated to Fatah had accepted half the proposals offered by Israeli authorities in response to the strike.
Around 500 of 3,000 Fatah affiliates are on hunger strike, along with 1,500 detainees linked to other political parties, the representatives said.
There are around 4,500 Palestinians jailed in Israel.
But Yousef Rizqa, political adviser to Hamas prime minister Ismail Haniyeh, warned on Monday that Israel was trying to use party affiliations to sow rifts between the hunger-strikers.
The government in Gaza insists only a completely successful response to demands will end the strike, as partial responses will negatively affect prisoners, he said.