United Nations ? The U.N. Security Council voted Thursday to extend the investigation into the assassination of Lebanon’s former prime minister but didn’t agree to Lebanon’s request to immediately broaden the probe and establish an international tribunal.

After a day of intense negotiations on how to characterize Syria’s dealings with U.N. investigators, the 15-nation council expressed “extreme concern” that the Syrian government has still not provided “the full and unconditional cooperation” it has demanded.

U.S. Ambassador John Bolton praised the resolution, which was adopted unanimously, saying “the United States believes it sends a strong signal to Syria that we still require full and unconditional compliance.”

The latest report by chief investigator Detlev Mehlis said new evidence strengthened his belief that the Syrian and Lebanese intelligence services had a hand in the Feb. 14 car bomb that killed Rafik Hariri and 20 others in Beirut. It said there were 19 suspects so far, including six high-ranking Syrian officials.

The resolution’s co-sponsors – the United States, France and Britain – faced opposition from Russia, China and Algeria not only on the extent of Syria’s cooperation but on expanding the probe and setting up an international tribunal.

Under pressure from Moscow, Beijing and Algiers, the co-sponsors backed away from their original resolution that would have immediately expanded the investigation to include a series of other terrorist attacks.

Instead, the resolution adopted Thursday authorizes the International Independent Investigation Commission led by Mehlis to provide technical assistance to Lebanese authorities in their probe of terrorist attacks since Oct. 1, 2004.

It also asked U.N. Secretary-General Kofi Annan, after consulting with the commission and the Lebanese government, “to present recommendations to expand the mandate of the commission to include investigations of those other attacks.”

As for Lebanon’s request for an international tribunal, the resolution also asked the secretary-general “to help the Lebanese government identify the nature and scope of the international assistance needed” and to report to the council.

The resolution extended the Investigation Commission’s mandate until June 15. The council asked the commission to report on its progress in three months and earlier if it decides Syria is not cooperating.