UNITED NATIONS (Reuters) - Secretary of State Colin Powell said on Thursday abandoning a U.S. peace plan would lead Israel and the Palestinians over the edge of a cliff and he urged Palestinian President Yasser Arafat to help stop attacks on Israel after a bomb killed 20 people in Jerusalem.

U.S. officials fear Tuesday´s attack by a suicide bomber from the Hamas militant group will unleash a fresh cycle of attack and retaliation, something that may already be happening as Israel killed a senior Hamas official and Palestinian militant groups called off their 7-week-old cease-fire.

Powell, the main advocate of the U.S.-backed peace plan that calls for the creation of a Palestinian state as early as 2005, insisted the so-called "road map" had not hit a dead end.

"The end of the road map is a cliff that both sides will fall off," Powell told reporters after a meeting with U.N. Secretary-General Kofi Annan that focused on a U.N. resolution to encourage others to provide troops and aid for Iraq after a truck bomb killed 24 people at the U.N. headquarters in Baghdad Tuesday.

"The alternative is what? Just more death and destruction, let the terrorists win, let those who have no interest in a Palestinian state win, let those who have no interest but killing innocent people win? No. That is not an acceptable outcome," he said. "Both parties realize it and I think both sides should recommit themselves to finding a way forward."

Powell´s appeal to Arafat, whom Washington has tried for months to marginalize, was an implicit acknowledgment that he retains influence and that Palestinian Prime Minister Mahmoud Abbas may not have the muscle to stop attacks on Israel.

"I call on Chairman Arafat to work with Prime Minister Abbas and to make available to Prime Minister Abbas those security elements that are under his control so that they can allow progress to be made on the road map -- end terror, end this violence that just results in the further repetition of the cycle that we´ve seen so often," Powell said.

PALESTINIAN AUTHORITY

At his daily briefing, State Department spokesman Richard Boucher said authority over Palestinian security organizations was still divided between Arafat and Abbas and said it needed to be firmly in the prime minister´s hands.

"That split still remains. There is still not clear authority over all the security apparatus. And in order to carry out the kind of serious and immediate steps that are needed right now, we think he (Abbas) does need to have control over all the security elements. And that´s what the secretary is pressing for," Boucher said.

Powell also called for all countries, including Arab nations, "to step up now and insist that the terror perpetrated by organizations such as Hamas must come to an end."

While he did not cite Syria by name, Powell has long called on Damascus to stop supporting Palestinian militant groups that the United States believes operate from Syrian territory.

The collapse of the temporary cease-fire declared by Palestinian militant groups on June 29 would be a major blow to U.S. efforts to end 34 months of Israeli-Palestinian violence that erupted after a previous round of U.S. peace talks under former U.S. President Bill Clinton ended in failure.

While the cease-fire had mixed results, it had markedly reduced Palestinian violence against Israelis. (© Reuters 2003 08/21/03)