RAMALLAH, West Bank - Israel released 429 Palestinian prisoners on Monday to bolster President Mahmoud Abbas after a U.S.-sponsored conference last week on Palestinian statehood, Israeli officials said.

The inmates, most of whom belong to Abbas's secular Fatah movement and were serving sentences ranging from 7 months to 15 years, were bussed from the desert prison of Kitsiyot to Israel's borders with the Gaza Strip and the occupied West Bank.

There are nearly 11,000 Palestinians held in Israeli jails. The Jewish state says most are there for involvement in militant groups behind a Palestinian revolt that erupted in 2000.

Israel's Prisons Service said 20 prisoners were sent to the Hamas-controlled Gaza Strip and 409 to a crossing near the West Bank city of Ramallah, where a formal homecoming reception took place attended by Palestinian Authority officials and families.

"The Israelis need to release those with long sentences to show they are serious about the peace process," said Abbas aide Tayeb Abdel-Rahim. "President Abbas has exerted maximum effort to keep the prisoner issue on top of the world's agenda."

Abbas and Israeli Prime Minister Ehud Olmert launched formal peace talks at the conference in Annapolis, Maryland. The plan is to reach a peace agreement by the end of 2008 as U.S. President George W. Bush winds up his term in office.

PEACE MOMENTUM

Israel has refused to commute sentences of Palestinians jailed over lethal militant attacks but Monday's release is meant to strengthen Abbas against Hamas Islamists who seized Gaza in June.

"Israel understands it is crucial to reinforce the political dialogue by concrete actions on the ground," said Israel government spokesman Mark Regev. "We are hopeful that today's release will help to contribute to the growing momentum in the political dialogue between us and the Palestinians."

Hamas has rejected the peace moves with Israel.

The Jewish state's forces have rounded up suspected militants in almost nightly raids on the West Bank and Gaza. Forty-two were detained on Monday, the Israeli army said.

One of those seized was Khaled Barbari. His family said he was taken by Israeli troops as he travelled to the homecoming celebration for his brother, Ahmad, who was freed on Monday.

"They simply made an exchange. They released Ahmad and arrested Khaled," said Mahmoud Barbari, another brother.

The Israeli army had no immediate comment on the case.

Families of prisoners who gathered at the Beitunia checkpoint outside Ramallah said they were happy to see their loved ones return, but noted most of the freed inmates had only a few months left to serve behind bars.

"My happiness is not complete because I want to see all prisoners released and see all mothers happy like I am today," said Bahiyeh Alayan, whose son Hamdallah was released after serving a 5-year term.

The issue of prisoners is highly emotive for Palestinians, who see their brethren held in Israeli jails as fighters against foreign occupation. Many Israelis fear that such amnesties encourage Palestinian militants to strike again.