President Bush on Friday said the U.N. should deal quickly and seriously with a report implicating Syria in the assassination of Lebanon's former prime minister, a killing that led to protests and withdrawal of Syrian troops from Lebanon after nearly 30 years as overlord.

"The report strongly suggests that the politically motivated assassination could not have taken place without Syrian involvement," Bush said.

In Damascus, Syrian leaders dismissed the findings, and the government of President Bashar Assad (search) prepared to fight growing Western sentiment to punish it with economic sanctions.

Imad Moustapha (search), Syrian ambassador to the United States, said the report was baseless and the Bush administration was motivated by Syria's opposition to the war in Iraq.

He said of the report, in Washington, "It will only help fuel anti-American sentiment around the world."

The report was likely to worsen the divisions between Lebanon's pro- and anti-Syrian groups. Syria's opponents in Lebanon welcomed the findings as the long-awaited truth about the assassination and about Syrian interference in Lebanese affairs. Pro-Syrian politicians vigorously criticized the findings.

The United Nations investigative report, which Bush called "deeply disturbing," made a link between high-ranking Syrian officials and their Lebanese allies in the car bombing that killed Rafik Hariri (search) and 20 others in February.

The findings and the reaction to them marked the latest escalation in tensions between the United States and Syria. U.S. officials have accused Damascus of harboring terrorist groups and permitting fighters to cross into Iraq to attack U.S., Iraqi and other forces there.

The report, issued Thursday to members of the U.N. Security Council, did not implicate Syrian President Assad directly, but said his government did not cooperate with the inquiry.

Bush spoke in California after helping dedicate a new pavilion at the Ronald Reagan Presidential Library and Museum.

He said he had telephoned Secretary of State Condoleezza Rice earlier in the day and instructed her to call on the United Nations to convene a Security Council session "as quickly as possible to deal with this very serious matter."

Bush was not specific about what steps the international community should take. He said the United States has started talking with U.N. officials and with Arab governments about that.

"Today a serious report came out that requires the world to look at very carefully and respond accordingly," Bush said.

The United States and France are readying Security Council resolutions critical of Syria.

The Security Council, which can impose political and economic sanctions, was already scheduled to meet next Tuesday to consider the report from German prosecutor Detlev Mehlis. The U.S. mission said Friday it had no plans to call for an earlier meeting time.

Separately, the U.N. will soon receive another report on Syrian compliance with last year's U.N. demand that it quit Lebanon and allow political self-determination there.

Rice, on a trip to Tuscaloosa, Ala., said, "Accountability is going to be very important for the international community."

Separately, the head of the State Department's Near East Bureau said Hariri was the victim of a "political crime."

"We would like to see those responsible for this crime and others in Lebanon brought to justice," Assistant Secretary of State C. David Welch said in Washington.

Although Rice has refused to rule out military action against Syria, the Bush administration stressed that it has no plans for military intervention.

"We are seeking a diplomatic solution to this problem," State Department spokesman Adam Ereli said Friday.

Washington withdrew its ambassador from Damascus immediately after Hariri's killing.

The French government, which joined with the United States to pressure Syria to withdraw its troops from Lebanon, said it also was holding consultations in the U.N. Security Council.

"The full consequences of this report must now be examined," the foreign ministry said in Paris.

At the time of Hariri's assassination, Syria had about 14,000 troops in Lebanon and essentially controlled the country along with its Lebanese government allies.

Hariri, once partially allied with Syria, had broken with Damascus and begun a political campaign to establish greater Lebanese independence.

The Mehlis report cited a witness who said Assef Shawkat, the president's brother-in-law and Syria's military intelligence chief, forced a man to tape a claim of responsibility for Hariri's killing 15 days before it occurred. The report also said Syrian Foreign Minister Farouk al-Sharaa lied in a letter to the investigating commission.

Assad's government repeated its claim of innocence in the Hariri killing and declared that the U.N. document was heavily politicized because of Syria's staunch anti-Israeli position.

Information Minister Mahdi Dakhlallah said the report lacked hard evidence and was based on witnesses "who are well known for their anti-Syria stands."