Israeli troops backed by tanks have moved into the West Bank town of Nablus, after Palestinian gunmen killed five Israelis in a Jewish settlement nearby.

About 50 tanks and a number of armoured bulldozers entered the city from four directions just before dawn.

There have also been clashes in the Gaza Strip, where four Palestinians were killed and one Israeli injured in three separate incidents.

Israeli forces were sent into other major Palestinian West Bank towns earlier this week, in response to two suicide bombings in Jerusalem this week that killed 26 Israelis.

Night raid

The Nablus incursion came a few hours after Palestinians killed five Israelis settlers - including three children and their mother - inside a house in the Itamar settlement.

We're in the valley and there aren't any fences here or anything

Itamar resident

The gunmen infiltrated the settlement after nightfall. They burst into a house, opening fire at the family inside and then shooting in all directions.

The family killed was named as Rachel Shabo, 40, and her sons Neria, 16, Zavi, 12, and Avishai, 5. A security guard also died in the attack.

The first gunman was killed as Israeli troops stormed the house. The other jumped out of a window and escaped. Itamar resident Rinat Cabara told Israeli television: "I was hanging laundry outside and I heard shots being fired so I ran home."

"When I entered I saw my husband with his gun near the window... We're in the valley and there aren't any fences here or anything."

Itamar was the scene of another attack on 28 May in which four Jewish students at an Orthodox seminary were shot dead.

Air attacks

In Gaza, three Palestinians were killed near the Erez crossing, when Israeli soldiers fired on a man who had thrown a grenade, killing the attacker and two workers.

Israeli troops had only recently pulled out of Palestinian towns

Also in the Gaza Strip, one Israeli has been wounded in a shooting incident at the Netzarim Jewish settlement.

Israeli tanks then made a brief incursion into the surrounding area and closed the coast road, before withdrawing.

These incidents come a day after Israeli helicopter gunships attacked and destroyed several Palestinian metal factories in the Gaza Strip, which they suspected of manufacturing weapons, and in the wake of the recent suicide attacks in Israel.

Those attacks prompted Israeli Prime Minister Ariel Sharon to press ahead with a new policy of seizing Palestinian land in retaliation.

Israeli call-up

There has been a partial call-up of Israeli reserve troops to allow the army to progressively reoccupy parts of the West Bank.

They will stay there until the suicide attacks are stopped, said Mr Sharon.

The BBC's Paul Wood in Jerusalem says the Israeli cabinet is deeply divided over whether it is possible or desirable for the army to reoccupy Palestinian towns.

The latest suicide bombings prompted Palestinian leader Yasser Arafat to call for an immediate halt to such attacks.

US President George W Bush has postponed a long-awaited speech on the Middle East peace process because of the upsurge in violence.

Israeli troops are now occupying most major West Bank towns with tanks, backed up by helicopters.