RAMALLAH (Reuters) -- An Egyptian-brokered deal that ended a mass hunger strike by Palestinian prisoners in Israeli jails has failed to meet hopes that Israel would change its policy of detention without trial.

In the two weeks since some 2,000 inmates agreed to end their hunger strike, more than 25 prisoners have either been rearrested after their release or had their six-month "administrative detention" terms renewed, Palestinian officials said on Monday.

The new detention figures, relating to Palestinians suspected of security offenses, are largely in line with past statistics during a two-week time frame, the officials said.

Under the deal, Israel agreed to reduce solitary confinement and increase family visits. The agreement contained no explicit mechanisms for ending detention without trial, but prisoners and negotiators believed it compelled Israel to curtail the practice and refer more cases to open courts.

"We think that the Palestinian side and the Egyptian side made the same mistake, which is leaving the Israeli side to determine what the language of the agreement means," said Mourad Jadallah, a representative of the prisoner advocacy group Addameer based in Ramallah in the occupied West Bank.

Israeli prison officials could not be immediately reached for comment.

Detention without trial has drawn international criticism. Israel says the practice is necessary because some cases cannot be brought to open court for fear of exposing Palestinian intelligence sources who have cooperated with Israel.

"Israel has taken our understandings to the furthest possible extreme," Jawad Boulos, one of the attorneys, told Palestinian radio. "This is sad, painful and angering, not just for us but for the prisoners who have had their terms extended three or four times."

Most of the 2,000 striking prisoners fasted for a month. But several others had refused food for up to 77 days - raising fears in Israel of a bloody Palestinian backlash if any of them died. Israel holds some 4,800 Palestinians in its jails.

Two prisoners refused to accept the deal, and remain on hunger strike. One of them, Mahmoud al-Sarsak, a football player from Gaza detained by Israel as an "unlawful combatant", has not eaten for 71 days.

In a desert prison in southern Israel, several dozen Hamas members detained without trial have threatened an open-ended hunger strike unless they are released, according to a handwritten letter seen by Reuters.