Five American nationals and two Israelis were killed in a bomb attack at Jerusalem's Hebrew University on Wednesday, it has been confirmed.

The Palestinian militant group Hamas said it carried out the attack which also left more than 80 people injured, including Arabs, South Koreans and Japanese attending summer courses at the university.

Witnesses described scenes of carnage

Israeli Defence Minister Benjamin Ben-Eliezer approved military retaliation against Hamas targets, but there were no details on the exact nature of the response, according to Israeli media reports.

Hamas warned it would kill 100 Israelis for any new attack on any of its leaders.

It said the attack on the university campus was in retaliation for an Israeli air strike on Gaza City last week in which 15 people were killed, including the group's military leader.

In a separate incident, the body of an Israeli man, his hands and feet bound, who had been shot dead was found near the West Bank town of Tulkarm, police said on Thursday.

Condemnation

The Palestinian Authority condemned the attack on the university - the second in as many days - but said Israeli Prime Minister Ariel Sharon was "responsible for this cycle of violence".

US President George W Bush condemned the attack "in the strongest terms".

"This terrorist attack underscores again the need for the Palestinian people and the Palestinian leadership to take action to halt terrorism so that peace has a chance in the Middle East," Mr Bush's spokesman Ari Fleischer said.

In a statement claiming responsibility for the attack, Hamas said: "It's a part of a series of responses that will take a long time and teach all Israelis."

Israeli police have been braced for bombings - reports say they have intelligence that as many as 60 attacks are being planned.

The blast at the Hebrew university was the second attack in the city within 24 hours.

The explosive was apparently left in a bag in one of the university's cafeterias, marking a change of tactics from using suicide bombers.

Israeli officials said some of the American victims had dual nationalities.

On Tuesday, a suicide bomber blew himself up outside a food stand in Jerusalem, injuring several Israelis and killing himself.