JERUSALEM - Israel rejected Palestinian President Mahmoud Abbas' request for a quick release of prisoners to bolster nascent peace moves, saying Friday that Palestinian militants must first free a captured Israeli soldier.

Palestinian President Mahmoud Abbas (R) attends Friday prayers at his headquarters in the West Bank city of Ramallah December 29, 2006. [Reuters]

The decision was a setback for the moderate Palestinian leader as he jockeyed with the radical Islamic Hamas group for popular support in the increasingly turbulent West Bank and Gaza. Abbas had hoped Israeli concessions would strengthen his argument that talks - not violence - are the Palestinians' best hope for achieving a state.

Israeli Prime Minister Ehud Olmert, himself fighting low approval ratings, has sought in recent weeks to re-energize his government with a push to revive long-stalled peace efforts with the Palestinians.

The Israeli newspaper Yediot Ahronot reported Friday that Olmert was prepared to hold back-channel talks to resolve the intractable disputes that derailed previous peace efforts, including the final borders of a Palestinian state, the status of Jerusalem and the fate of Palestinian refugees. Olmert spokeswoman Miri Eisin declined to comment on the report.

Abbas said he had proposed the backdoor talks with Olmert at their summit last week, and the Israeli leader promised to consider it. Abbas did not say why he sought secret talks, But as an architect of the 1993 Oslo peace accord that was negotiated secretly between Israel and the Palestinians, he is known to champion quiet, informal diplomacy.

The Israeli government has tried to quietly strengthen Abbas, of the Fatah Party, in his rivalry with Hamas, a radical group that won control of the Palestinian parliament and Cabinet in January elections. The dispute between the groups has exploded into open warfare on Gaza's streets in recent weeks.

At his summit with Abbas, Olmert offered to ease West Bank travel restrictions and to give the Palestinian leader $100 million in Palestinian funds that Israel froze after Hamas' election victory. Olmert also urged his Cabinet to consider a small prisoner release as a gesture to Abbas ahead of the Eid al-Adha holiday, which starts Saturday.

That appeared to be a softening of the government's earlier stance that it would not free any prisoners until the Hamas-linked militants who captured Cpl. Gilad Shalit in June release the Israeli soldier. The militants had demanded a wide-scale prisoner release, but Olmert refused, saying it would reward the militants, and instead launched a major Gaza offensive.

On Friday, with the Muslim holiday approaching, chances of a swift prisoner release appeared to have disappeared.

"Right now, it's not on the agenda," as long as Shalit remains captive, Eisin said.

Cabinet minister Zeev Boim told Israel Radio that a release, common at holiday time, "must not happen today because it would be misinterpreted."

Abbas aide Saeb Erekat said Olmert was probably reluctant to buck Israeli public pressure not to release any of the 8,000 Palestinian prisoners until Shalit is released. "It's unfortunate," Erekat said, adding that the decision would hurt Abbas' domestic standing.

One of the Hamas-linked groups holding Shalit said Thursday that progress has been made toward a prisoner exchange, and media quoted Palestinian Prime Minister Ismail Haniyeh of Hamas as saying the soldier would be released soon. But neither said when a swap might take place, and previous claims of progress have not panned out.

Shalit's father, Noam, who has been critical of Israel's efforts to free his son, said he supported a pre-holiday prisoner release.

"I thought it might generate some positive momentum toward a final deal to free Gilad and other prisoners," he told Israel Radio.

Shalit's parents also published an open letter to their son Friday in Arabic in the east Jerusalem daily, Al-Quds.

"We will do everything so that your release and that of the Palestinian prisoners will take place soon," the letter said. "We hope the men of the Palestinian organization are generous enough to show you this letter from your parents, just as we hope that Israeli authorities treat the Palestinian prisoners well and allow them to receive and send letters to their parents."

Relatives of Palestinian prisoners said they were disappointed that they would not be reunited with their loved ones ahead of the holiday.

Samir al Halabi, a father of a 19-year-old Palestinian prisoner, said he and other Palestinian parents were emotionally split.

"We are 50 percent optimistic and 50 percent not," he said. "I didn't expect my son to be (released), but I still have hope he will be included with the prisoners released in return for Gilad Shalit."

Israel ended its Gaza offensive last month after agreeing to a cease-fire with the Palestinians. Since then, Palestinian militants in Gaza have launched more than 80 rockets into Israel, including nine on Friday. Olmert has told the military to abandon its policy of restraint and attack the rocket squads, though it has yet to do so.