Western powers and the Arab League have demanded immediate UN action to stop Syria's "killing machine" but Russia refused to give its support, as fighting on the ground intensified.
The wrangling at the United Nations on Tuesday came as fierce clashes raged across Syria's powderkeg regions between President Bashar al-Assad's security forces and rebel fighters of the Free Syrian Army.
Activists said on Wednesday the unrest had killed nearly 200 people in the past three days, including 28 civilians on Tuesday.
US Secretary of State Hillary Clinton, backed by her French and British counterparts as well as Qatar's prime minister, led the charge for a tough UN resolution that would call on Assad to end the bloodshed and hand over power.
"We all know that change is coming to Syria. Despite its ruthless tactics, the Assad regime's reign of terror will end," Clinton told the UN Security Council.
"The question for us is: how many more innocent civilians will die before this country is able to move forward?"
Analysts warn that the conflict in Syria, between a guerrilla movement backed by growing numbers of army deserters and a regime increasingly bent on repression, has largely eclipsed the peaceful protests witnessed at the start of the uprising.
"It is the beginning of an all-out armed conflict," said Joshua Landis, head of the Centre for Middle East Studies at the University of Oklahoma.
"We are heading toward real chaos," he added. "The Syrian public in general is beginning to (realise) that there isn't a magic ending to this, there isn't a regime collapse.
"People had hoped that by peaceful demonstrations they would cause Bashar al-Assad to resign or he would run away, or that there would be a Tahrir Square moment," Landis said, referring to the epicentre of Egypt's mass protests that toppled Hosni Mubarak last year.
"All that turned out to be wishful thinking."
The United Nations says more than 5,400 people have been killed in Syria since the pro-democracy uprising began in March last year.
But UN human rights chief Navi Pillay said on January 25 her organisation had stopped compiling a death toll for Syria's crackdown on the protests because it is too difficult to get information.
Qatari Prime Minister Sheikh Hamad bin Jassim Al-Thani, speaking at the Security Council on behalf of the Arab League, said Assad's regime had "failed to make any sincere effort" to end the crisis and believed the only solution was "to kill its own people."
"Bloodshed continued and the killing machine is still at work," he said.
But Russia, a longstanding ally of Assad and one of the regime's top suppliers of weapons, declared that the UN body did not have the authority to impose such a resolution. China voiced support for Russia's position.
Moscow's ambassador to the UN, Vitaly Churkin, argued that Syria should "be able to decide for itself" and said the Council "cannot impose the parameters for an internal settlement. It simply does not have the mandate to do so."
However, the tone of Tuesday's debate was measured and Churkin said that the latest version of the resolution "gives rise for hope."
"We hope that the Council will come to consensus on the Syrian issue, as is not only possible but also necessary," he said.
France also held out the possibility of a successful UN resolution and said that diplomats would pursue talks.
The key sticking point appeared to be the Arab League call for Assad's speedy departure.
"Regime change is not our profession," Russian Foreign Minister Sergei Lavrov said during a trip to Australia.
The draft resolution, introduced by Arab League member Morocco, calls for the formation of a unity government leading to "transparent and free elections."
It stresses that there will be no foreign military intervention in Syria as there was in Libya, helping to topple Moamer Kadhafi.
In Washington, US intelligence chief James Clapper said the fall of the Assad regime was in any case inevitable, while warning that it could take "a long time."
But Syria remained defiant, with UN ambassador Bashar Jaafari saying his country would "stand firm in confronting its enemies."
He accused the Western-Arab alliance of "double standards" and of "fomenting the crisis."
Meanwhile, the rebel Free Syrian Army said half of the country was now effectively a no-go zone for the security forces.
"Fifty percent of Syrian territory is no longer under the control of the regime," its Turkey-based commander Colonel Riyadh al-Asaad told AFP.
He said the morale of government troops was extremely low. "That's why they are bombing indiscriminately, killing men, women and children," he said.