The United States and France put the finishing touches on a UN Security Council resolution Tuesday that is expected to demand Syria reverse a pattern of obstruction and cooperate with a probe into the assassination of Lebanon's former prime minister. A central question remains whether the resolution will threaten sanctions or other punitive action if Syria doesn't cooperate with the probe into Rafik Hariri's Feb. 14 assassination, as investigators claim. Russia and China, which can veto a resolution, may try to block such a move. "We want a very strong signal to the government of Syria that its obstruction has to cease and cease immediately," US Ambassador John Bolton said. "The resolution will be very clear that the spotlight's on Syria and that it's obstruction today cannot continue." Bolton spoke after the council heard a briefing from the chief investigator of the probe, Detlev Mehlis, who had delivered a report five days ago implicating top Syrian and Lebanese security officials in the car bomb that killed Hariri and 20 other people on Feb. 14. Mehlis has said repeatedly that Syria had not fully cooperated and continuing the probe would be near impossible if Damascus didn't change course. He took that message directly to the council in his briefing, urging Syria to help "fill in the gaps" about who orchestrated the bombing, both by cooperating with a probe and studying the crime itself. "The Syrian authorities may wish to carry out on their part their own investigation into the assassination of Mr. Hariri in an open and transparent manner," he said. Mehlis was more blunt in comments to reporters later in the afternoon. "I cannot send 500 investigators, which I do not have, to Syria to look for documents because I do not know where I would find them," he said. "It would be a good idea if the Syrian authorities made an extra effort by themselves." Mehlis' report, made public last Thursday, caused an uproar in the region and brought swift denials from the Syrian government, which called the report biased, politicized and an American plot to take over the region. It raised questions about the possible involvement of Syrian President Bashar Assad's brother-in-law and Lebanon's pro-Syrian president, Emile Lahoud. Syrian officials and Lahoud deny that they were involved in Hariri's assassination and have reiterated several times that they have cooperated fully with Mehlis' probe. Syria's UN Ambassador Fayssal Mekdad told the council Tuesday that every paragraph in the Mehlis report deserved to be refuted. He criticized Mehlis for accusing Damascus before the end of the investigation. The commission "should not have pointed the finger or cast doubt on anybody," he said. Syria "has cooperated faithfully and sincerely with the Independent International Commission" and will continue to do so, he said. In Washington, US President George W. Bush used a speech on Iraq and the broader war on terror to prod the Security Council on Syria. "Now the United Nations must act, and Syria and its leaders must be held accountable for their continuing support of terrorism, including any involvement in the murder of Prime Minister Hariri," Bush said in a speech at a luncheon at the officer's club on Bolling Air Force Base. The Security Council has discussed scheduling a meeting for Monday, attended by the 15 members' foreign ministers, to adopt a resolution. Diplomats say their presence would give the resolution added weight and increase pressure on Syria. Several diplomats said council members all agree that Syria must cooperate more and want a strong resolution demanding it. They appear to disagree, however, on how to back up a call for more involvement from Syria. Russia and China - both veto-wielding members of the council - don't appear in any hurry, and Moscow, which has close ties to Syria, would likely oppose sanctions or any reference to them. "My government is always very cautious with such sensitive issues as Syria-Lebanon," Russia's UN Ambassador Andrey Denisov said Monday. France indicated Monday it would not support sanctions against Syria before Mehlis finished his investigation. US Secretary of State Condoleezza Rice also has indicated the United States might be willing to put off its push for sanctions. Mehlis had asked for and received an extension of his mandate until Dec. 15, something he said would "provide yet another opportunity for the Syrian authorities to show greater and meaningful cooperation." Mehlis said his team will reinterview a number of witnesses, interview some for the first time and complete its examination of new evidence. He told reporters that Syria had also agreed to turn over the autopsy report of Syrian Interior Minister Ghazi Kenaan, who was questioned by investigators and committed suicide in his office on Oct. 12. Kenaan effectively controlled the Lebanese government for 20 years as Syria's intelligence chief. Syria said Kenaan committed suicide, but some in Lebanon and at least one veteran U.S. mediator for the Middle East suggested he may have been killed in an attempted cover-up of Syrian involvement in Hariri's killing. Mehlis also called for stepped up security for his team of 30 investigators from 17 countries in the aftermath of the report. "The commission has received a number of threats which were deemed, in the assessment of our security personnel, to be credible," he said.