Russia and China have vetoed an Arab and Western-backed resolution at the United Nations Security Council condemning the violent crackdown in Syria.
The two permanent members of the council rejected the draft resolution on Saturday, despite strong condemnation by United States president Barack Obama of the latest violence in the city of Homs, the BBC reports.
Early accounts of the casualties talked of as many as 200 deaths, but one of the main activist groups later revised its confirmed toll down to 55.
Mr Obama described the attack as an "unspeakable assault", but the Syrian government dismissed the reports as fabricated.
Western governments criticised Russia and China for standing by Syria and its crackdown on an 11-month uprising against its leader Bashar al-Assad.
The Americans said the two countries had sold out the Syrian people; the French accused them of backing Damascus without scruple; while the British said they had turned their backs on the Arab world.
The US ambassador to the UN, Susan Rice, says she is disgusted by the Russian and Chinese veto, adding that any further bloodshed will be on their hands.
"The international community must protect the Syrian people from this abhorrent brutality. But a couple of members of this council remain steadfast in their willingness to sell out the Syrian people and shield a craven tyrant."
The vote at the UN in New York was delayed by about two hours as Russia tried to win support for amendments to the draft.
The Russians were still unhappy with the Arab plan for a political transition which the resolution endorses, saying it imposes a solution on Syria.
They also wanted language condemning the armed opposition as well as the Syrian army. This, in particular, was a step too far for Western diplomats.
It is the second time that permanent UN members Russia and China have exercised a double veto on the Syria issue.
In October last year, they vetoed a European-drafted resolution condemning Syria and threatening it with possible sanctions.
Russia is Syria's main ally on the council and Moscow has continued to supply weapons to Syria despite the protests.
Syrian demonstrators have ransacked their country's embassy in Cairo and broke into the missions in London, Kuwait and Canberra among protests around the world against the bloodshed.
Protesters have attacked other embassies in Europe and the Middle East.
Rallies have also been held outside embassies in Germany, the United States, Greece and Libya.