Jerusalem ? Israel and the Palestinians agreed to a cease-fire Saturday to end a five-month Israeli military offensive in the Gaza Strip and the firing of rockets by Palestinian militants into the Jewish state, but early violations by Palestinian militants tempered hopes the accord would help revive long-stalled peace talks.

The Israeli military said early Sunday that it withdrew all its troops from Gaza in the hours before the 6 a.m. cease-fire took effect. But occasional rocket and mortar fire from Gaza continued to strike Israel within the truce’s first hour.

“Let’s hope that’s just the problems of the beginning,” Israeli government spokeswoman Miri Eisin said. “But if Israel is attacked, we will respond. If there are Palestinian factions that are not part of the cease-fire, it’s hard to see how the cease-fire will hold.”

All militant factions denied involvement in the attacks.

A spokesman for the Palestinian government, Ghazi Hamad, said all armed groups have committed to the agreement and termed any violations rogue acts.

“There is 100 percent effort to make this work, but there is no guarantee of 100 percent results,” Hamad said.

The truce agreement, if it holds, would be a significant achievement for Palestinian President Mahmoud Abbas as he tries to put together a more moderate government to replace the one currently led by Islamic Hamas radicals. Abbas, a moderate from the Fatah Party, hopes a deal with Hamas will persuade the West and Israel to lift crushing economic sanctions against the Palestinians.

The sides announced the cease-fire Saturday after Abbas telephoned Israeli Prime Minister Ehud Olmert late Saturday to tell him he had arrived at an agreement with all Palestinian factions – including those allied with Hamas – to stop all rocket attacks and suicide bombings from Gaza.

Abbas asked that Israel, in turn, stop its military operations in Gaza and withdraw its forces, and Olmert agreed, spokespeople for both leaders said.

Abbas spokesman Nabil Abu Rdeneh said from Gaza City that Palestinian Prime Minister Ismail Haniyeh of Hamas and the Palestinian factions had agreed to reinstate a truce between Israel and the Palestinians reached in Egypt in February 2005.

Earlier in the day, various militant factions denied reaching a cease-fire agreement. But after it was officially announced, they acknowledged the accord and said the denials were linked to power struggles among them.