Britain and the US rounded on the Syrian government yesterday, recalling embassy staff and issuing stern warnings to the regime to end its fierce crackdown on dissent.
The move came as a renewed assault on the opposition stronghold of Homs was reported to have left dozens more people dead.
The surge in violence prompted the US to close its embassy in Damascus and pull all American diplomats out of the country. William Hague, the British Foreign Secretary, said he had summoned the Syrian ambassador in London to express his "abhorrence at violence that is utterly unacceptable to the civilised world".
Mr Hague also said in a statement to the House of Commons that he was recalling the British ambassador in Damascus for consultations, after the breakdown at the UN on Saturday of a united diplomatic front.
Leaving no doubt that he blames the Assad government for the "appalling" bloodshed and repression, he said the regime was "doomed" because of its actions. "The Syrian regime has deployed snipers, tanks, artillery and mortars against civilian protesters and population centres, particularly in the cities of Homs, Idlib, Hama and Deraa.
"Thousands of Syrians have endured imprisonment, torture and sexual violence – including instances of the alleged rape of children – and the humanitarian position is deteriorating. The human suffering in Syria is already unimaginable and is in grave danger of escalating further."
The double veto by China and Russia of the Arab League-backed plan calling on all sides to halt violence and for a peaceful transition of power has left Arab and Western nations scratching their heads over the best way to proceed.
The US has called for a "Friends of Syria" group to be set up to help unite the opposition groups and provide more humanitarian aid, but Western leaders remain adamant that military action is not on the table.
"Not every situation is going to allow for the kind of military solution we saw with Libya," said Barack Obama.
Al-Jazeera television shows footage taken by activists showing explosions and plumes of smoke rising from what they said were neighbourhoods of Homs. The UN says more than 5,600 people have been killed since the demonstrations began last year.
In central Damascus, it was business as usual with roads snarled with traffic and a light security presence. But some reports suggested that just 20 miles outside the capital there was fierce shelling of the mountain town of Zabadani, which came under effective rebel control in January.