Palestinian Prime Minister Mahmoud Abbas, facing growing international pressure to clamp down on Islamic groups, convened an emergency Cabinet meeting Wednesday to decide how to respond to a Hamas bombing that killed 20 Jewish settlers. The Cabinet did not announce a decision after its two-hour session, except to say the rule of law in the West Bank and Gaza Strip would be enforced. The final say is up to Yasser Arafat and top PLO officials, who will meet later Wednesday with Cabinet ministers. Earlier Wednesday, Palestinian security chief Mohammed Dahlan met with Palestinian security commanders in the Gaza Strip, ordering them "to be on high alert to implement whatever decision will be taken by the political leadership and the Palestinian Authority against those who were involved in yesterday's attack in Jerusalem," spokesman Elias Zananiri said. Abbas, who could lose his job if violence persists, has said he will not confront the Islamic groups - as required by the peace plan - because he fears internal fighting. Ariel Sharon and top defense officials decided Wednesday to give Dahlan time to begin cracking down on the 'militants', a security official said on condition of anonymity. Abbas was meeting with Islamic Jihad leaders in Gaza City on Tuesday when he learned of the bombing. Condemning the attack as a "terrible crime," Abbas also broke off contact with Hamas and Islamic Jihad, called off upcoming trips to Italy and Norway, and convened the emergency Cabinet meeting. U.N. Secretary-General Kofi Annan urged Abbas "to take decisive action to arrest the instigators of this attack and prevent such attacks from happening again," U.N. spokesman Fred Eckhard said in New York. Yasser Abed Rabbo, the Palestinian Minister for Negotiations with Israel, said, "We have decided to boycott Hamas and Islamic Jihad, and at the same time the Palestinian leadership has instructed the Palestinian cabinet and the Palestinian security services to take all necessary measures in order to preserve the Palestinian national interests." In the Gaza Strip, Hamas leaders insisted Wednesday they remain committed to a three-month truce they and other militants declared unilaterally on June 29, but said they reserve the right to revenge the killings of operatives by Israeli troops. In the meantime, Israel froze all contacts with the Palestinian Authority and canceled the planned handover of two West Bank towns to Palestinian control, a move that was expected later this week. The Israeli army also closed border crossings to seal off the West Bank and Gaza Strip. Palestinian legislator Saeb Erekat criticized Israel's decision, saying it was important to maintain contacts. "The main message I want to send to the Americans is that ... every possible effort should be exerted to keep the road map and the truce alive," he said. **PHOTO CAPTION*** Abdel-Hamid Mask, a 29-year-old imam from the West Bank city of Hebron, blew himself up aboard a Jerusalem bus on August 19, 2003. (Reuters)