The United Nations has raised "grave concern" about the conditions of hundreds of Palestinian prisoners who have gone on a mass hunger strike in Israeli jails, DPA reported.
The Israel Prison Service (IPS) said Thursday that the number of those refusing to take food had climbed from 1,350 to almost 1,600.
UN Reliefs and Works Agency (UNRWA) Commissioner General Filippo Grandi issued a statement "appealing to the Israeli government to find an acceptable solution."
Secretary-General Ban Ki-moon made a similar call Wednesday, saying he was following developments with concern and demanding that those held in so-called "administrative detention" be either tried or released immediately.
Some 300 Palestinians are held under special provisions that allow Israel to jail suspected militants without charge, based on classified intelligence material that is only shown to a military judge, for extendable six-month periods.
The hunger strikers demand their release, as well as better conditions, including visits from their relatives in Gaza.
Most have been refusing food since April 17, a date marked as annual Palestinian Prisoners Day.
Two of them, Bilal Diab and Thaer Halahleh of the radical Islamic Jihad movement, have now been on hunger strike for more than 70 days, well beyond the critical 45-day mark set by the World Medical Association.
IPS spokeswoman Sivan Weizman denied, however, that the two were in life-threatening condition, claiming they were not on a "full" hunger strike because they were getting vitamins and minerals through intravenous drips.
Diab was briefly taken to a civilian hospital, but returned to the IPS medical facility in Ramle, near Tel Aviv, on Tuesday.