Palestinian gunmen have ambushed an Israeli army patrol in the West Bank, killing three soldiers and wounding several others. The attack Sunday was the most serious of its kind in recent months against Israeli troops.

Israeli security officials said that Israeli soldiers were on foot patrol when they came under fire east of the West Bank city of Ramallah. Israel radio reported the Palestinian assailants detonated an explosive and threw grenades during the deadly ambush.

The Israeli military immediately placed a curfew on the Jewish settlement of Ein Yarbrud, situated close to where the soldiers were targeted, as a search got underway for the attackers.

The Al-Aqsa Martyrs Brigades, an armed wing of Palestinian President Yasser Arafat's Fatah faction, claimed responsibility for the attack.

The ambush came just hours after Palestinians in Gaza fired home-made Kassam rockets at towns in the Negev area of Israel.

Meanwhile, the Speaker of the Israeli parliament, Rueven Rivlin, said that security is being strengthened around the Knesset in Jerusalem following intelligence that it has also become a prime target for Palestinian terrorist attacks. "We had some specific warnings and we know that all the time the terrorists are planning the possibility to hit the Knesset because it will bring them a lot of prestige," he said.

Mr. Rivlin made his comments ahead of the start on Monday of a new session of the Israeli parliament.

Israeli Prime Minister Ariel Sharon is scheduled to make an address to the parliament, touching on a range of issues, including the security situation. On Sunday, Mr. Sharon's government ordered the call-up of five battalions of reserve soldiers amid warnings that Palestinian militants are planning to launch a new wave of suicide bombings and other attacks.

Some of the soldiers will be stationed to protect Israeli towns situated close to the West Bank, while others will be positioned in the Jordan Valley and the Gaza Strip.