A top Palestinian militant serving a 30-year sentence in an Israeli jail, was on Monday rushed to hospital after collapsing following 21 days without food, his deputy said.
Ahmed Saadat, secretary-general of the Popular Front for the Liberation of Palestine (PFLP) began an open-ended hunger strike on September 27 to protest being held in solitary confinement for the last four years.
The PFLP chief was soon joined by hundreds more prisoners, with all of them refusing food and drinking only water.
But Saadat's health has deteriorated significantly, his deputy told AFP on Monday, saying he was being transferred to a military hospital.
"Ahmed Saadat is now on his way to hospital because after 20 days of hunger strike, his health has really deteriorated," Abdulrahim Maaluf said.
But a spokeswoman for Israel Prisons Service (IPS) refused to comment whether or not Saadat had been taken to hospital, telling AFP: "His condition is satisfactory."
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She said there were currently 170 prisoners observing a hunger strike, down from the 234 inmates who were refusing food last week.
News of Saadat's deterioration came a day before Israel was to free a first tranche of 477 security prisoners in exchange for the release of Gilad Shalit, an Israeli soldier who was snatched by Gaza-based militants in June 2006.
Israel will in total release 1,027 prisoners, with a second group of 550 to be freed within the next two months.
But officials were quick to rule out the release of high-profile prisoners such as Saadat and the influential Fatah leader Marwan Barghuti.
The landmark prisoner swap deal which was signed by Israel and Hamas last Tuesday, also reportedly included an Israeli commitment to improve conditions for the remaining prisoners, and to end the practice of solitary confinement.
But Weizman refused to comment on the report.
More than 5,000 prisoners are held in jails across Israel, the vast majority of whom are serving time for security offences.
Israel has accused Saadat of masterminding the killing of Israeli tourism minister Rehavam Zeevi exactly 10 years ago, on October 17, 2001.