DHARAMSHALA, July 20: Just hours before the expiry of a UN observer mission in Syria, China and Russia, for the third time vetoed a UN Security Council resolution Thursday that would have punished the Syrian government with economic sanctions for failing to carry out a peace plan.

The resolution would have given Syrian President Bashar al-Assad 10 days to put the peace plan — which he accepted three months ago but has basically ignored — into effect. The resolution would have imposed economic sanctions on the Syrian government under Chapter 7 of the United Nations Charter. That section of the charter also allows for military intervention to enforce Security Council demands.

The Security Council vote has left in limbo the future of a 300-member United Nations mission in Syria that was sent to monitor the peace plan, which was negotiated by Kofi Annan, the special envoy of the United Nations and the Arab League.

Observers believe the veto, aimed at halting the 16-month conflict that has killed thousands will spark dire warnings of even greater bloodshed and spillover to the wider region.

"The effect of their actions is to protect a brutal regime. They have chosen to put their national interests ahead of the lives of millions of Syrians," British ambassador, Sir Mark Lyall Grant, told the 15-member Security Council after the vote.

U.N. Secretary-General Ban Ki-moon, who visited Beijing earlier this week and discussed the issue with Chinese President Hu Jintao, said he was "deeply disappointed" by the Security Council. "The hour is grave. The international community has a collective responsibility to the Syrian people," he said in a statement.

The U.S. ambassador to the United Nations, Susan Rice, called the Russian and Chinese moves "dangerous and deplorable" and said the Security Council had "failed utterly."

International mediator Kofi Annan, who had sought a tough resolution to save his disintegrating peace plan, also voiced disappointment, saying the council had failed to take "the strong and concerted action" he had hoped for.

China's UN Ambassador Li Baodong hit out at Western criticism of his country's vote.

"Certain countries in their remarks just now have confused right with wrong, and criticised China for no reason. This is totally wrong and has ulterior motives. The Chinese side is resolutely opposed to this," Li said.

The Security Council initially approved the deployment of the observer mission, known as UNSMIS, to monitor a failed April 12 ceasefire. UNSMIS suspended most of its monitoring activity on June 16 due to increased risk from rising violence.

Russia and China have maintained a track record of supporting each other on the council to protect their respective allies from interference, such as Iran, North Korea and Sudan.