Troops destroyed the family home of Khamis Jarwan, who was identified by Palestinian and Israeli sources as being responsible for the first bombing at a shopping centre in Rosh Haayin, near Tel Aviv.

Israeli police are on nationwide alert and have been setting up roadblocks on key roads and at the entrances to Israeli towns in an attempt to head off any further attacks.

Israeli army radio said intelligence sources had warnings of some 20 impending attacks ? up from seven or eight daily warnings a week ago ? although none of them have been specific. The al-Aqsa Martyrs Brigades claimed responsibility for the Tel Aviv attack, while Hamas said it was behind the second bombing outside a Jewish settlement in the occupied West Bank. The two militant groups said they carried out the attacks ? in which two Israelis as well as the bombers died ? in retaliation for an Israeli raid last week.

But the two groups stressed they were still sticking to a militant ceasefire that was declared in June. Israeli officials say they have refrained from major military retaliation, saying Israel wants to achieve calm to advance on the ?roadmap? plan for peace. The United States has condemned the two suicide bombings which it says threaten a shaky Middle East truce.

?I?ll kill whoever dispatched my son?

The two suicide bombers, Khamis Jarwan and Islam Qteishat, both 17, were teenagers living near each other in the Askar refugee camp in Nablus, the scene of last week?s Israeli raid.

Israeli army bulldozers remained in the area, raising the possibility that the second bomber?s house would be destroyed as well. Israeli forces routinely demolish houses belonging to Palestinian militants.

An Israeli army statement said: ?The demolition of houses of terrorists sends a message to suicide bombers and their partners that anyone who participated in terrorist activity will pay a price for their actions.?

Amnesty International told the demolitions were effectively a breach of the Geneva Conventions. ?This incident is yet a further instance of quite unlawful collective punishments practised systematically by the Israeli authorities for over a year,? said an Amnesty spokesman. ?They have included the demolition of homes of bombers as well as those suspected ? not convicted ? of crimes. Amnesty International calls on Israel to stop perpetrating collective punishments, which only further endanger any hope of a peace process.?

The mother of Khamis Jarwan demanded retribution against the militants who sent her son to die. She told the Associated Press news agency: ?I?ll kill whoever dispatched my son.? The attacks were condemned by both the Palestinian Prime Minister, Mahmoud Abbas ? known as Abu Mazen and his Israeli counterpart, Ariel Sharon. Israel delayed the release of 76 Palestinian prisoners on Tuesday, following the attacks. They had already boarded buses when they were ordered back to prison.