Nearly twice that number, 2,300 inmates, said they will return their meals for the day, Ynetnews.com said.
In an act of solidarity, eight foreign activists, who participated in the flytilla to Israel earlier this week and are being held until deportation, said they would join the Palestinian prisoners, the Web site said.
The strike coincides with Palestinian Prisoner Day and the Israeli prison authorities' refusal to grant demands that include access to more television stations, higher education and an end to isolation for their leaders, the site said.
The prisoners are also demanding Israel end its administrative detention policy, which permits detainees to be held indefinitely without charge, and allow visits from Gaza relatives. Negotiations had been under way to avert the hunger strike but failed, Haaretz said.
Palestinian prison minister Issa Qaraqi told the British daily The Guardian the situation in Israeli prisons is "dangerous and serious."
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