The council's fifth meeting in four days heard Georgia bring another appeal to stop Russia's army, which UN officials confirmed had driven deep beyond Georgia's breakaway regions of South Ossetia and Abkhazia.
Irakli Alasania, Georgia's ambassador, told reporters after the session that "a full military invasion of Georgia is going on" and that the "security council has to act".
Russian military moves
The UN officials, Lynn Pascoe and Edmond Mulet, advised the council behind closed doors on Monday that non-peacekeeping Russian airborne troops were entering US-allied Georgia from Abkhazia, and were not meeting any resistance while taking control of Georgia's Senaki army base, council diplomats said.
They also said that three airborne battalions had been deployed to reinforce a 2,500-strong Russian allied peacekeeping force at the ceasefire line between Abkhazia and Georgia, the diplomats said on condition of anonymity.
Western diplomats said the observations by the UN officials seemed to confirm their suspicions about Russia's motives.
"If the Russian intent, as has been stated, has been the return to the status quo ante in South Ossetia, why start a second front from Abkhazia? Why attack the rest of Georgia? And why attack the infrastructure of Georgia? Why threaten to attack the civilian airport of Tbilisi?" Zalmay Khalilzad, the US ambassador, said to reporters.
He said whether the French proposed draft passes or not "depends exclusively on Russia" and it was time for the council to take "the necessary action".
"The United States is not looking for hostile relations between Russia and the United States, that's not our goal. We want this conflict to be resolved, a ceasefire to go into effect as quickly as possible.
"But we cannot be indifferent to what is happening in Georgia … and as I said before, that as this conflict continues, it will have significant impact on the relationship between us and Russia," Khalilzad added.
His comments echoed those of George Bush, the US president, who demanded on Monday that Russia end a "dramatic and brutal escalation" of violence in Georgia, agree to an immediate ceasefire and accept international mediation to end the crisis in the former Soviet republic.
Bush warned Russia in his strongest comments since the fighting erupted to "reverse the course it appears to be on" and abandon any effort to overturn Georgia's pro-Western government.
But the rhetoric is unlikely to be backed by military action, Al Jazeera's correspondent at the UN, John Terrett, said.
The US has little leverage with a resurgent Moscow, and the White House needs Russia to help it press Iran over Tehran's nuclear ambitions.
If the Georgians had hoped that by providing troops in Iraq and publicly expressing a desire to join Nato they would gain the US military's protection - they were now surely disappointed, our correspondent said.
In Tbilisi on Monday, Georgia's president said Russian troops had in effect cut his country in half by seizing Gori, a strategic city along the country's main east-west highway and only about 100km west of the capital.
In the face of the military reality, Mikail Saakashvili signed a EU-proposed ceasefire declaration and appealed to the "world's consciousness" over what he said was Russia's true goal: undermining his government.
Bernard Kouchner, the French foreign minister who got Saakashvili to sign the document in Tbilisi, was heading to the Russian capital with the signed peace document on Tuesday in the hopes that Moscow would come on board too.
"We're going to Moscow, to see it from the other side. They will be able to agree on this document and we have some hope but of course it's always the same thing with a peacekeeping mission, it takes time," Kouchner said.
But Russian envoy Churkin's comments to reporters regarding Saakashvili at the UN on Monday does not bode well for the peace effort.
"We in Russia, we cannot see how we can do business with him," Churkin said. "We make no secret of that."
Al Jazeera's Neave Barker, reporting from Moscow, said the Russian government was frustrated at the West's apparent lack of concern for what it says is genocide in South Ossetia committed by the Georgians and it is expected to raise that with Kouchner when he visits.