Islamic Jihad yesterday threatened to avenge Monday's killing of senior West Bank leader Luay Sa'adi as tens of thousands of Palestinian mourners buried him yesterday morning in Tul Karm.

Sa'adi was killed during a shootout with Israel Defense Forces troops, sparking a new round of violence.

In the early hours of Monday morning, IDF troops stormed the house where Sa'adi, 26, the leader of Islamic Jihad's military wing in the West Bank and the number-one wanted man there for months, was meeting with other senior leaders of the organization to plan a suicide attack against Israel, according to military and Shin Bet security service sources. While the operation was underway, a car pulled up to the house, and the commander of the force and his radio operator approached it. The radio operator was slightly injured in the shoulder by a single bullet fired from inside the car. The two returned fire and killed the passenger in the back seat, subsequently identified as Mager Ashkar, 26, a senior operative in Sa'adi's ring.

Sa'adi initially escaped from the house into the alleys of Tul Karm, but ran into troops and was killed in an exchange of fire. One IDF officer was slightly wounded by shrapnel. The troops were unaware of Sa'adi's identity until after he was killed.

A few hours after Sa'adi was killed, Islamic Jihad militants launched five Qassam rockets into Israel from the Gaza Strip.

Sa'adi has been directly implicated in the suicide bombing of the Stage club in Tel Aviv in February, when five people were killed and 49 wounded, as well as the suicide bombing in July near the Sharon mall in Netanya, where five people were killed and dozens injured. Sa'adi had also planned to blow up a booby-trapped car in the settlement of Shavei Shomron on the same day as the Sharon mall attack. He has been involved in several shooting attacks, including the one that killed Yvgeny Reider, 28, of Hermesh in the West Bank in June.

Also in June, Sa'adi attempted to carry out a double attack in Jerusalem, assisted by Islamic Jihad activists from Bethlehem; the explosive belts had already reached the capital when the attack was thwarted by the security forces.

Islamic Jihad has ignored the cease-fire agreement attained in January among the various Palestinian groups.

Israel, which has said it would act harshly against any attacks from Gaza following its withdrawal from the area last month, responded to the Qassam attacks by launching a missile strike in the southern Gaza town of Rafah, hitting a building that housed a pro-Jihad charity. The attack moderately wounded a 65-year-old woman and a 4-month-old baby, and lightly hurt three others, Palestinian health officials said.

The IDF also fired missiles from a helicopter into empty fields in northern Gaza from where the militants launched the rockets.

Palestinian Authority Chairman Mahmoud Abbas yesterday condemned Sa'adi's killing and Islamic Jihad's retaliation, which he called "silly."

"We don't accept the Israeli aggression and we don't accept the silly responses that lead to the punishment of the [Palestinian] people," Abbas said.

Palestinian militants ultimately ceased their fire once the PA deployed police officers near their launching sites.

Meanwhile, the Erez and Karni border crossings between Israel and the Gaza Strip were closed Monday night. The closure, in effect until further notice, is considered a means of putting pressure on the PA to prevent Qassam fire.

The five Qassam rockets that sparked off the recent exchange of fire in Gaza slammed into open areas near the western Negev town of Sderot. There were no reports of casualties or damage. Palestinian witnesses said one of the rockets apparently misfired and hit a mourning tent for a dead Palestinian in northern Gaza. There were no reports of Palestinian casualties from the IDF artillery shelling.

The killing of Sa'adi will cripple the terrorist infrastructure in the West Bank in both the short and the long term, according to Colonel Aharon Haliba, the new commander of the IDF's Ephraim Brigade. "However I have no doubt a replacement will be found for them, as they always do," Haliba said.