Israeli security forces have gone on high alert for possible terror attacks before the week-long sacred Jewish Passover holiday, which begins at sunset on Monday. Israel says a closure imposed on the West Bank and Gaza Strip last month is to remain in force for weeks to come.

Israel's secret police, the Shin Bet, says it has received about 60 warnings of planned terror attacks during the Passover holiday.

Security officials say the warnings include efforts to launch a large-scale attack to avenge Israel's assassination of Hamas spiritual leader Sheikh Ahmed Yassin last month.

Hamas and the Islamic Jihad claimed joint responsibility for the killing on Saturday of an Israeli man in a Jewish settlement in the West Bank, saying it was in revenge for the sheikh's death.

Both groups are listed by the State Department as terrorist organizations and have carried out frequent suicide bombings and other attacks that have killed hundreds of Israelis.

The Palestinian responsible for Saturday's attack on the Jewish settlement was identified as a member of Hamas. He was shot and killed by Israeli forces, who then demolished his family home in the Palestinian refugee camp in the West Bank town of Tulkarem.

Israel often demolishes the homes of Palestinians responsible for the killing of Israelis, saying it is meant to deter others from carrying out such attacks.

The Palestinian leadership condemns the policy as a form of collective punishment.

Meanwhile, Israeli Defense Minister Shaul Mofaz said a closure imposed on the Palestinian territories last month will remain in force until after the country celebrates its Independence Day in late April. He says this is necessary for Israel's security.

The decision means that thousands of Palestinians whose livelihood depends on entering Israel for work will be prevented from doing so until the closure has been lifted.