JERUSALEM - Bowing to pressure from Washington, Israel granted U.S.-trained Palestinian security forces greater autonomy in four main West Bank towns, Israeli and Palestinian defence officials said Thursday.

The ability of Palestinian security forces to maintain law and order is key to Mideast peacemaking because Israel needs to be convinced that a future Palestinian state won't threaten its security.

Israel already has turned over security control to Palestinians in three other West Bank towns. Israeli officials said the army would now reduce its presence in four more population centres -- Qalqiliya, Bethlehem, Jericho and Ramallah.

In a statement, the Israeli military said Palestinian security forces "will be able to extend their hours of operation" in the towns but emphasized that Israeli forces would continue to operate in the West Bank "in order to thwart terrorist operations."

The move stops short of a full withdrawal from these towns.

However, Israeli will ease its requirement that Palestinian security forces in these towns co-ordinate their movements closely with the Israeli military. This would allow the Palestinians to decide for themselves things like where to deploy, and where they should be armed and uniformed, an Israeli official said.

The Israeli military doesn't routinely patrol West Bank towns and cities, but frequently conducts nighttime and occasional daytime arrest raids.

Israel pulled out of major West Bank population centres in the 1990s but re-entered them after the Palestinian uprising against Israel reignited in late 2000. Palestinians have long sought an Israeli pullback from those towns as a reassertion of sovereignty.

The U.S. has been training thousands of forces in the West Bank in preparation for future Palestinian statehood. The European Union has contributed about $55 million (40 million euros) for equipment and training, said Jose Vericat, an EU official.

Israel says the Palestinian force has improved and has relinquished routine security duties in major West Bank towns, including Jenin, a one-time militant stronghold that has become a showcase for the force.

"We are doing our job protecting our people and there is no need for Israeli forces to enter our territories under the pretext of security needs," said Adnan Dmeiri, a spokesman for the Palestinian security forces.

Another apparent result of U.S. pressure has been the recent removal of some of the hundreds of Israeli roadblocks, including major obstacles near the city of Nablus and town of Jericho. Israel insists it needs the checkpoints to stop attackers but has also said it is committed to making life easier for Palestinians.

Israel, however, has been wary of a complete handover to Palestinian security.

During the Palestinian uprising, some Palestinian forces turned their guns against Israeli targets. And police loyal to Palestinian President Mahmoud Abbas, were unable to hold back the onslaught of Islamic Hamas militants in the Gaza Strip in 2007. Abbas now only controls the West Bank, while Gaza remains under Hamas control.

Also Thursday, an Israeli soldier captured by Palestinian militants marked his third anniversary in captivity in Gaza, with no news on his plight.

Sgt. Gilad Schalit, 22, was captured on June 25, 2006, by Hamas-affiliated militants who tunneled under the Gaza-Israel border and attacked a military post. Two other soldiers were killed in the raid.

Schalit has not been seen since and the Red Cross has not been allowed to visit him, though Hamas has released two recorded statements from him and exchanged letters between him and his family. Former President Jimmy Carter delivered a letter from Schalit's parents to Hamas officials last week.

Egyptian-mediated attempts to arrange a prisoner swap between Israel and Hamas have been unsuccessful. A Hamas spokesman, Osama Almuzeini, said Thursday that there were no new developments in the negotiations.

He refused to confirm whether the soldier was alive or dead, saying Hamas would not give any "information for free." Hamas has demanded the release of hundreds of prisoners, including people convicted in deadly attacks on Israelis, in exchange for the soldier.