Israel’s stepped-up campaign in the coastal territory has prompted the Palestinians to warn that peace talks between President Mahmoud Abbas and Prime Minister Ehud Olmert, spurred by a visit by US President George W Bush, were in jeopardy.

Israel has killed more than 30 Palestinians in Gaza since Monday, including one militant and a civilian in a missile strike on Friday morning.

The Israeli army says it is targeting Gaza militants who have fired more than 110 rockets into the Jewish state in the last three days alone.

In the West Bank city of Nablus, Israeli troops killed a militant linked to Abbas’s Fatah movement.

 The Israeli Defence Ministry ordered all of the border crossings with Gaza closed and said only “humanitarian cases”, which receive Defence Minister Ehud Barak’s personal approval will be allowed through.

“If milk is low in Gaza, the minister will be asked to approve a milk shipment, and it will enter,” a Defence Ministry spokesman said.

Gaza is home to 1.5 million people, most of whom depend on foreign aid.

The United Nations Relief and Works Agency (UNRWA), which provides food to refugees, said it was not allowed to deliver truckloads of supplies on Friday morning as it usually does.

“Gaza is completely shut down. This will only add to an already dire situation,” said UNRWA spokesman Christopher Gunness.

Israel has imposed strict curbs on non-humanitarian supplies to Gaza since June when Hamas Islamists seized the coastal territory after routing Abbas’s forces.

Many essentials have been getting in, either with Israeli approval or through smuggling, though supplies are limited and prices have risen sharply. “It is inconceivable that we are opening the crossings for the Palestinians and risking our people’s lives,” the Defence Ministry spokesman said.

Signal to Hamas
“This is a signal to Hamas that it needs to contemplate if it wants to continue with this situation... The meaning is not to starve the population of Gaza," the spokesman added.

Gunness said UNRWA has enough supplies in Gaza to last up to two months, but that the UN rations provide only a portion of the food that recipients need.

Olmert vowed on Thursday to wage a "war" on Gaza militants.

 But he gave no indication he might order a large-scale ground operation.