Hundreds of Palestinians in Israeli prisons have declared a hunger strike, in a new wave of protest that Palestinian officials said was expected to grow.
Some of the hunger strikers accused Israeli prison guards of "harassment" while others refused food in solidarity with prisoner Bilal Kayed, who has been fasting for 52 days over his continued detention without trial, Palestinian officials said.
The Palestinian Prisoners Club said in a statement that 80 prisoners stopped eating on Friday, joining 325 who have been fasting for the past two days at various prisons in Israel and the occupied West Bank.
More were expected to join the hunger strike from Sunday.
The Palestinian Authority detainee affairs commission told AFP news agency that inmates are protesting against a prison crackdown this week, in which a number of inmates were placed in solitary confinement, personal belongings were seized and prisoners moved to other facilities.
It said that hunger strikers were being fined $158 each, and forbidden visits for two months.
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An Israeli prison official said that a large part of the protest appeared to be in response to a decision by authorities to hold prisoners from the group Hamas in separate cells.
The Israel Prisons Service said that during the week it had moved Hamas prisoners, searched cells and seized mobile phones, acting on "intelligence information about direction of terror from inside prisons".
A spokesman told AFP that there were currently 262 Hamas prisoners on hunger strike, along with 93 from the group Popular Front for the Liberation of Palestine (PFLP) who are fasting in solidarity with Kayed.
Kayed was to be released in June after serving a 14-and-a-half-year sentence for activities in the PFLP, labelled a terrorist organisation by Israel, the European Union and the US.
Instead, Israeli authorities ordered that he remain in custody under an administrative detention law, which allows prisoners to be held without trial for renewable six-month periods.
Kayed, 35, is suffering from failing kidneys and has lost at least 30 kilos, Palestinian officials said.
Administrative detention is intended by Israel to allow authorities to hold suspects while continuing to gather evidence, with the aim of preventing further attacks in the meantime.
The system has been criticised by Palestinians, human rights groups and members of the international community.
Of more than 7,500 Palestinians currently in Israeli jails, around 700 are being held under administrative detention, Palestinian rights groups said.
Palestinians have regularly gone on hunger strike to protest their detention.