Britain has condemned as "inexcusable and indefensible" the decision by Russia and China to veto a United Nations Security Council resolution threatening sanctions against the regime of president Bashar Assad in Syria.
The vetoes came just hours after Prime Minister David Cameron issued a direct plea to Russian president Vladimir Putin not to block action against Assad, warning that Syria faces civil war unless the dictator leaves. "The alternative to political transition at the top of Syria is revolution from the bottom in Syria," warned Mr Cameron during a visit to Afghanistan.
As fighting continued for the fifth day on the streets of the capital Damascus, Foreign Secretary William Hague accused Moscow and Beijing of turning their backs on the people of Syria "in their darkest hour".
Mr Hague said Britain would now back a proposal from peace envoy Kofi Annan for a final 30-day extension of the UN observer mission in Syria after its mandate runs out on Friday, in order to give the Assad regime "a last opportunity to live up to its commitments".
But the UK will also seek tighter EU sanctions and look at what more it can do to help the Syrian opposition, he said.
And he made clear that, while Thursday's resolution would not have authorised military action, the door had not been closed on the use of force in future, saying that Britain "will rule nothing out" in its efforts to end the killing.
In a warning to those in positions of power in Damascus, the Foreign Secretary said: "Today's veto does nothing to change the fact that the Assad regime is doomed. My message to all those in the regime is that they will be held accountable for their actions. The pressure on them will not relent for an instant in spite of the veto today. We will do all that we can do to end the killing and will rule nothing out in the future in these efforts."
Thursday's developments in New York came a day after the most daring strike by rebels since the outset of the uprising 16 months ago, when a bomb killed three leading regime figures, including Assad's brother-in-law and the defence minister, attending a crisis meeting in Damascus. Rumours circulated that Assad himself may have been injured in the blast or have fled the capital with his British-born wife Asma, but state TV showed footage of him swearing in a new defence minister.
The Security Council voted 11-2 in favour of a resolution which would have created a trigger for global sanctions if Damascus failed to live up to commitments to end the use of heavy weapons against insurgents and civilians, to step back from violence, permit UN observers to operate unhindered and move towards a political resolution.
But China and Russia were able to block agreement by wielding the vetoes they hold as permanent members of the 15-nation Council. They instead backed a rival Russian resolution which would extend the observer mission by up to 90 days but was dismissed by the UK as ineffective.