Updated

Russia is blocking Western efforts to push through a Security Council resolution that would raise the prospect of sanctions against Syria unless the government gives unrestricted access to deliver humanitarian aid.

Russia's U.N. Ambassador Vitaly Churkin vowed to veto the proposed measure if necessary. Both he and China's U.N. ambassador were no-shows at a meeting Monday to discuss the Western and Arab-backed resolution.

"This text would not have any positive impact on the situation," Churkin said, explaining why Russia didn't bother to attend the meeting. "If anything, it would create disruption of humanitarian efforts."

Churkin dismissed the resolution as a "political" measure introduced "to whip up political tensions around Syria."

Russia and China, which support the Syrian government, have blocked three previous Western-backed resolutions that would have pressured President Bashar Assad to end the now three-year-old civil war.

The divided Security Council did come together in October to approve a presidential statement appealing for immediate access to all areas of Syria to deliver aid. Western and Arab countries want to go a step further with a legally binding resolution but Russia's opposition dooms their effort.

Churkin made clear Russia would veto the resolution if it is put to a vote before the 15-member Security Council.

"This text is not going to be adopted, I can tell you," he said.

Russia is "talking about things that the Security Council can conceivably do usefully in order to improve the humanitarian situation in Syria," Churkin said. "If we produce something ... which is pragmatically useful and will go to a vote I hope it will be adopted."

He said hard, pragmatic work is needed to address the "enormous" humanitarian problems in Syria.

Churkin said positive developments have allowed humanitarian workers to evacuate hundreds of civilians and deliver aid to besieged areas of the rebel-held city of Homs.

U.N. humanitarian chief Valerie Amos welcomed a three-day extension of the initial three-day "humanitarian pause" in Homs. She said local authorities and representatives of all sides, working "in extremely dangerous circumstances," have evacuated more than 800 people from Old Homs and brought food and medical supplies to people who have had little aid for nearly two years.

But Amos said "it is absolutely unacceptable" that U.N. and Syrian Red Crescent aid workers were targeted, and that 11 people lost their lives needlessly because the parties didn't maintain their ceasefire during the initial pause.

The proposed Security Council resolution, obtained by the Associated Press, puts most of the blame for the humanitarian crisis on the Syrian government.

If demands for unrestricted humanitarian access are not granted within 15 days, the resolution expresses the council's intention to impose non-military sanctions against individuals and entities responsible for the obstruction of aid deliveries.

The draft resolution expresses "outrage at the unacceptable and escalating level of violence and the death of over 136,000 people in Syria, including more than 11,000 children."