UNITED NATIONS — Top Syrian intelligence officials approved the assassination of former Lebanese Prime Minister Rafik Hariri and their Lebanese counterparts helped organize it, according to a U.N. probe that officially linked Damascus to the slaying for the first time.

The exhaustive report into the Feb. 14 car bomb that killed the popular opposition leader and 20 others stopped short of fingering Syrian President Bashar Assad or his inner circle. But it accused the regime of failing to cooperate in the probe and alleged Syrian Foreign Minister Farouk al-Sharaa lied in a letter to the investigating commission.

It also cites one witness as saying Assad's brother-in-law Assef Shawkat, who is Syria's military intelligence chief, set up a false confession to Hariri's murder 15 days before it took place.

Syria rejected the report.

Chief investigator Detlev Mehlis' findings were issued to the U.N. Security Council late Thursday and will almost certainly inflame tensions in the region.

The Security Council is likely to use the report to renew pressure on Syria to ease its continued influence on Lebanon. The council is expected to discuss it on Tuesday, and may consider sanctions against Syria.

The decision to assassinate Hariri "could not have been taken without the approval of top-ranked Syrian security officials and could not have been further organized without the collusion of their counterparts in the Lebanese security services," the report said.

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.

Mehlis was careful not to assign blame but cites witness testimony that strongly implicates several officials suspected of conspiring to assassinate Hariri. Lebanon has already arrested four of them, all Lebanese generals close to Syria.

The report also raised questions about Lebanon's pro-Syrian president, Emile Lahoud, alleging he received a phone call minutes before the deadly blast from the brother of a prominent member of a pro-Syrian group. The same man also called one of four generals arrested, Brig. Gen. Raymond Azar, who at the time was head of Lebanon's military intelligence.

Lahoud's office said it "categorically denies" that the president received such a phone call.

The 53-page report outlines Hariri's worsening relationship with Syrian officials and said the motive for his killing appeared to have been political. Hariri had fallen out with Syria and eventually resigned as prime minister in October 2004, a month after a decision to change Lebanon's laws and extend Lahoud's term.

Pro-Syrian opponents had accused Hariri of being the driving force behind a U.N. resolution adopted in September 2004 that unsuccessfully attempted to stop Lebanon's parliament from extending the term of Lahoud, Hariri's longtime rival. The resolution also demanded Syria withdraw all its troops and intelligence operatives from Lebanon.

The report cites one Syrian witness living in Lebanon who claimed to have worked for Syrian intelligence. He said Lebanese and Syrian officials decided to assassinate Hariri about two weeks after the Security Council adopted the resolution. At the beginning of January 2005, a senior Syrian officer in Lebanon told the witness: "Hariri was a big problem to Syria."

"Approximately a month later the officer told the witness that there soon would be an 'earthquake' that would rewrite the history of Lebanon," the report said.

The report quoted another witness as saying Brig. Gen. Mustafa Hamdan, another of the four Lebanese generals under arrest, ended an October 2004 conversation by saying: "We are going to send him on a trip, bye, bye Hariri." The witnesses were not identified.