Russia, China again veto Syria resolution in U.N. Updated at 11:21 a.m. (CBS/AP) UNITED NATIONS - Russia and China have again vetoed a Western-backed U.N. resolution threatening non-military sanctions against Syria. It was aimed at stepping up pressure on President Bashar Assad's government to end the escalating 16-month conflict. Thursday's 11-2 vote, with two abstentions, leaves in limbo the future of the 300-strong U.N. observer mission in Syria, whose mandate expires Friday. Britain's U.N. Ambassador Mark Lyall Grant, who sponsored the Western-backed draft, said he was "appalled" at the third double veto by Russia and China, allies of the Assad regime. Special Section: The Arab Spring Where is Bashar Assad? International envoy Kofi Annan had urged the U.N. Security Council to postpone Wednesday's scheduled vote so members could "unite and take concerted and strong action that would help stem the bloodshed in Syria and build momentum for a political transition," his spokesman Ahmad Fawzi said. The failed resolution threatened non-military sanctions against Assad's government if he doesn't withdraw troops and heavy weapons from populated areas within 10 days. Russia, which is a close Syrian ally, argued that the British proposal amounted to support for the rebels and would lead to more bloodshed. Russia and China have incurred international criticism by vetoing the past two U.N. resolutions to increase pressure on Assad. U.N. Secretary-General Ban Ki-moon, who was visiting China, also urged the Security Council to "take collective action, with a sense of unity." After a phone call from President Obama to Russian President Vladimir Putin on Wednesday afternoon, the Russian and U.S. ambassadors met at the United Nations but there was no breakthrough. Russia could put its rival text - which makes no mention of sanctions or Chapter 7 - to a vote. But diplomats said Moscow doesn't have the minimum nine "yes" votes required for Security Council approval, so that appears unlikely. Diplomats, speaking on condition of anonymity because talks have been private, said a simple resolution extending it for perhaps 30 days is the most likely scenario. The unarmed observers were authorized for 90 days to monitor a cease-fire and implementation of Annan's six-point peace plan. The U.S. and its European allies contend that with violence escalating dramatically and the failure to implement Annan's plan, there must be consequences for non-compliance. Diplomats have been scrambling to try to get council to unify, which would send a much stronger signal to Syria. According to the White House, Putin and Mr. Obama agreed that the growing violence in Syria shows the need for a political transition as soon as possible - a key demand of the Annan plan. But the Kremlin said they didn't agree on the measures that need to be taken.