The violence occurred outside the West Bank town of Qalqilya during riots over Israel's handling of the release of Palestinian prisoners under the Wye River land-for-peace deal signed in Washington in October.

The Palestinian leadership has protested at what it said was the firing of live rounds into crowds engaged in peaceful protest.

Paul Adams: President Clinton's most difficult Middle East mission yet

The deaths brought to four the number of Palestinians killed by Israeli forces this week. More than 200 have been injured in the almost daily street battles.

Clashes over the prisoner issue have cast a shadow over US President Bill Clinton's three-day visit.

Palestinian and Israeli forces, reinforced by US security teams, are on high alert in preparation for the visit. Correspondents say traffic and normal life in Jerusalem is expected to grind to a halt when he arrives.

Israeli Prime Minister Binyamin Netanyahu has ordered his security forces to deal with any unrest with a very firm hand.

On Friday, Mr Netanyahu reiterated his conditions for resuming the withdrawal of Israeli troops from the West Bank.

He told Israeli television that the Palestine National Council must take a formal vote to cancel clauses in its charter calling for Israel's destruction. The Palestinians have said no vote is necessary.

President Clinton will visit Gaza on Monday, an event which Israeli right-wingers protest amounts to a symbolic US endorsement of a Palestinian state.

BBC Jerusalem Correspondent Jeremy Bowen reports

US Secretary of State Madeleine Albright tried to soothe Israeli concerns on Friday by saying any Palestinian state would have to be negotiated through the peace process as part of so-called "final status" talks on a permanent Middle East peace agreement.

"The issue of the Palestinian state, as we have said many, many times, is not an issue that is going to be declared unilaterally or be strengthened by various symbols," Mrs Albright said.

Controversial prisoner issue

Israel says it agreed at Wye to release 750 Palestinian prisoners in three groups over three months but has insisted that none should have "blood on their hands".

It included 150 common criminals in a first group freed last month, angering Palestinians who say Israel should release "political detainees".

Mrs Albright said the prisoner dispute needed to be dealt with through the proper channels.