Israeli Prime Minister Ariel Sharon has threatened to freeze peace efforts with the Palestinians if they do not crack down on militant groups.
Speaking Sunday, Mr. Sharon said Syrian-based elements of the Palestinian group Islamic Jihad were responsible for Friday's suicide bombing outside a Tel Aviv nighclub.
The attack killed four Israelis and shattered a two-week old informal cease-fire agreement between Israel and the Palestinians.
Mr. Sharon called on Palestinian Authority President Mahmoud Abbas to act "vigorously" against militant groups -- saying there will be no diplomatic progress until such a step is taken.
The warning came as Syrian officials denied any role in Friday's bombing.
Islamic Jihad claimed responsibility for the attack, and Israeli officials have accused Damascus of supporting the militants.