The U.N. Security Council voted unanimously Thursday to extend the investigation into the assassination of Lebanon's former prime minister but didn't agree to Beirut's request to 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 council expressed "extreme concern" that the Syrian government still has not provided the commission probing the killing of Rafik Hariri with "full and unconditional cooperation."