Israeli troops have been ordered to withdraw from Palestinian-controlled areas of the West Bank.

The move is in response to a request from Washington to ease the military blockade and improve the climate for the visit of U.S. Middle East envoy Anthony Zinni, who is due to arrive later Thursday.

Israeli troops are withdrawing from Palestinian ruled towns in the West Bank, and have completed a pull out from Jenin and from neighborhoods in Ramallah.

The army announced it was also lifting blockades around the cities of Qaqilyah, Hebron and Tulkarem, but would remain in parts of Ramallah and Nablus.

The Israeli army took up the positions in the Palestinian cities in December, following a spate of suicide bombings that left 26 Israelis dead and hundreds wounded.

But following a drop in the violence, Israeli Prime Minister Ariel Sharon ordered the army to ease the living conditions of Palestinians, including removing roadblocks.

Washington encouraged the move in preparation for the visit of U.S. Middle East envoy Anthony Zinni, who wants both sides to adhere to a cease-fire agreement and enable the resumption of peace talks.

The Palestinian leadership is expecting Mr. Zinni, a retired Marine Corps general, to draft a timetable for the implementation of recommendations of an international inquiry into the violence, headed by former U.S. Senator George Mitchell.

But Raanan Gissin a spokesman for Prime Minister Sharon says Israelis are not ready for that countdown to begin without a period of seven days of complete quiet.

"We hope that this arrival of General Zinni in the area will really enable us to start counting those seven days of quiet and those will come about, only if the Palestinian Authority takes real steps to dismantle the terrorist infrastructure that it built," Mr. Gissin said.

A spokesman for the Israeli army says that there are still warnings of possible terror attacks.

He adds that while troops have pulled out of neighborhoods in the western part of Ramallah, they would remain in the north of the city, close to the headquarters of Palestinian leader Yasser Arafat.

The Israeli Government has imposed a ban on Mr. Arafat leaving Ramallah, until he agrees to arrest and hand over those Palestinians suspected of assassinating the Israeli Tourism Minister Rehavam Ze'evi in October.