Israel steps up Palestinian arrests

Most of those held have been freed, the army says

More than 4,000 Palestinians have been detained during Israel's offensive in the West Bank, the army says.

The figure - which has doubled in the past 24 hours - reflects the growing pace of the military campaign, correspondents say.

The mission is still on... I'm looking forward to the opportunity to meet with Prime Minister Sharon and with Chairman Arafat

US Secretary of State Colin Powell

US Secretary of State Colin Powell has arrived in Israel to try to secure a ceasefire and implement a step-by-step plan leading both sides back to peace talks.

However, Prime Minister Ariel Sharon has told Washington that it should not put Israel under pressure to end its military offensive against Palestinian militants.

An Israeli army spokesman said most of the Palestinians rounded up during the offensive were released shortly afterwards, once their identification had been checked.

Click for a detailed guide to the West Bank operation

Detainees were held at an army base in the West Bank and included more than 100 men on Israel's list of most wanted suspects.

They could be held for up to 18 days before being taken before a judge.

Tough mission

The American Secretary of State arrives in Israel from Amman where he held talks with Jordan's King Abdullah.

He is due to meet Mr Sharon on Friday, and the Palestinian leader Yasser Arafat on Saturday.

Speaking after a phone call with Mr Sharon, Mr Powell stressed the need to get into political talks however long the current offensive lasts.

	Israel's West Bank operation

However he did not repeat the US call for an immediate Israeli withdrawal from the West Bank.

The BBC's Jonny Dymond in Jerusalem says no one in Israel is expressing much optimism about Mr Powell's visit.

In the hours before his arrival, Israeli troops occupied three more areas in the West Bank and withdrew from several others.

Tanks and troops entered the town of Bir Zeit, the refugee camp of Ein Beit Elma near Ramallah and Daharyeh village near Hebron, and are reported to be carrying out house-to-house searches.

In Bir Zeit, troops reportedly took over the police station and witnesses said soldiers ordered students out of their dormitories at Bir Zeit University, detaining several of them.

Overnight Israeli forces retreated from Yatta, Qabatiya and Samua - four days after they swept into the autonomous areas as part of Operation Defensive Shield.

They say they have withdrawn from 24 small towns and villages altogether.

'Finishing the job'

On a visit to the West Bank town of Jenin, the scene of some of the fiercest fighting, the Israeli prime minister rebuffed calls for Israel to halt its offensive.

"We will continue to operate against the terror and its infrastructure," he said.

Mr Sharon said Israel was engaged in a war for its survival and the army had to "finish the job".

Jordan's King Abdullah II helped the Palestinian aid effort

Israel took control of Jenin on Wednesday after about 300 Palestinians, including armed fighters, surrendered to Israeli troops.

Unconfirmed reports on Thursday said another group of gunmen had given themselves up in Jenin.

Twenty-eight Israeli soldiers and more than 100 Palestinians were killed in eight days of fighting in the town, which has been declared a closed military zone.

On Thursday the BBC's James Reynolds managed to get into Jenin to the outskirts of the refugee camp, witnessing empty streets, damaged buildings and rubble on the road before being told to stop filming and leave by Israeli soldiers.

Bethlehem standoff

Troops also remain in Ramallah, Nablus and Bethlehem - where a stand-off continues around the Church of the Nativity, the traditional birthplace of Jesus Christ.

There are still more than 100 armed men inside the church, and the Israeli army says that among them are 30 militants on its wanted list.

The standoff at Manger Square continues

A suggestion by Christian leaders that the gunmen be granted safe passage to the Gaza Strip has been rejected by the Israelis, one of the negotiators told the BBC.

The BBC's Caroline Hawley said she saw black smoke billowing from the direction of Manger Square after hearing a series of explosions.

There was no immediate comment from the Israeli army, but Palestinians living nearby said that soldiers had blown up several cars on a nearby street.

For a second day, the Israel army has had a surveillance balloon hovering over the compound.

In Jordan, King Abdullah II and Queen Rania helped load food and medicines onto five helicopters due to fly the aid to the West Bank Palestinians on Thursday.