The United States is pushing for a tough resolution against Syria (search) that would include sanctions against the Syrian government and individuals named in the U.N. report that implicates Damascus in the killing of a Lebanese leader, a U.S. official told FOX News.

"This is true confessions time now for the government of Syria," U.S. Ambassador John Bolton (search) said to reporters at the U.N. on Monday. "No more obstruction. No more half measures. We want substantive cooperation and we want it immediately."

The report, prepared by chief U.N. investigator Detlev Mehlis, alleges high-ranking Syrian and Lebanese security officers were behind the Feb. 14 assassination of former Lebanese Prime Minister Rafik Hariri (search).

The United States is working with its allies, including Britain, in preparing the resolution, which will be tabled at a Security Council meeting on Tuesday just after Mehlis presents his report, a diplomat said.

But France, which has veto power on the council, said it would not consider sanctions until the end of the probe.

"We have here an opportunity to do justice with an independent inquiry. Let's go to the end ... if we need to make it longer, let's do it, and afterwards let's see what the consequences should be, including on the question ... of sanctions," Foreign Minister Philippe Douste-Blazy said.

Meanwhile, in Syria, the official SANA (search) news agency said hundreds of thousands of people gathered in Damascus and Aleppo to demonstrate against the "unjust accusations" made in the report, released last week by Mehlis.

The mass demonstrations in Syria were a concerted attempt to drum up support for President Bashar Assad amid heightening international pressure.

"Mr. Mehlis: We are not murderers," read one banner. "Syria will never be another Iraq," said another in central Damascus' Sabe Bahrat Square, where the crowd chanted: "With our soul and our blood, we redeem you, Bashar!"

Many demonstrators waved large posters of the Syrian president and his father, the late President Hafez Assad.

The government gave students a one-day holiday and encouraged civil servants to take part in the rallies, which were organized by state-run labor unions. Police diverted traffic to make way for the protesters.

Addressing the Damascus crowd from a balcony, a speaker said: "The masses of our people stand united in Arab Damascus today to condemn Mehlis' report and to declare their absolute rejection of the continuing U.S. threats against Syria. These threats have been stepped up since the occupation of Iraq."

State newspapers published editorials condemning the U.N. report, which found Hariri's assassination could not have been carried out without the complicity of Syrian and Lebanese intelligence services.

Syria's government has long argued that it is being attacked by the West because of its uncompromising stand on the Israeli-Palestinian dispute and Israel's occupation of Arab land.

For more than a year, Washington has been increasing pressure on Syria, accusing it of interfering in Lebanon's affairs, allowing insurgents to cross into Iraq and supporting Palestinian militant groups. Syria denies these charges.

Mehlis was scheduled to brief the Security Council on the report at an open meeting Tuesday.

While the United States, France and Britain have strongly supported his findings and are demanding Syrian cooperation, Russia and China have been much more reticent. All five countries have power to veto any action by the council.

Said Russia's U.N. ambassador, Andrey Denisov: "My government is always very cautious with such sensitive issues as Syria-Lebanon."

The Associated Press contributed to this report.