Russia and China vetoed a European-backed UN Security Council resolution that threatened sanctions against Syria if it did not halt its military crackdown against civilians.
It would have been the first legally binding resolution adopted by the Security Council since President Bashar Assad's military began using tanks and soldiers against protesters in mid-March.
Its defeat on reflects the deep divisions in the UN's most powerful body over how to address the violence in Syria, which the UN estimates has led to more than 2,700 deaths.
The European sponsors of the resolution tried to avoid a veto by watering down the language on sanctions three times, to the point where the word "sanctions" was taken out, but they failed.
The vote was 9-2 with four abstentions - India, South Africa, Brazil and Lebanon.
It was the first double veto by Russia and China since July 2008 when they blocked proposed sanctions against Zimbabwe. In January 2007, they also vetoed a resolution calling on Burma to release all political prisoners, initiate a wide-ranging dialogue and end military attacks and human rights abuses.
Russia's UN Ambassador Vitaly Churkin told the council after the vote that his country did not support the Assad regime or the violence but opposed the resolution because it was "based on a philosophy of confrontation," contained "an ultimatum of sanctions" and was against a peaceful settlement of a crisis. He also complained that the resolution did not call for the Syrian opposition to disassociate itself from "extremists" and enter into dialogue.
China's Ambassador Li Bandong said his country is concerned about the violence and wants to see speedy reforms but opposed the resolution because "sanctions, or threat of sanctions, do not help the situation in Syria but rather complicates the situation."
Supporters of the resolution expressed disappointment and outrage.
France's UN Ambassador Gerard Araud called the veto "a rejection of the extraordinary movement in support of freedom and democracy that is the Arab Spring" and commended "all of those who fight against the bloodthirsty crackdown in Syria."
Britain's UN Ambassador Mark Lyall Grant said the veto "will be a great disappointment to the people of Syria and the wider region that some members of this council could not show their support for their struggle for basic human rights."
"By blocking this resolution, the onus is now on those countries to step up their efforts and persuade the Syrian government to end the violence and pursue genuine reform," he said.
US Ambassador Susan Rice said "the courageous people of Syria can now clearly see who on this council supports their yearning for liberty and human rights - and who does not."
She accused Russia and China of wanting to sell arms to the Syrian regime rather than stand with the Syrian people - an accusation vehemently denied by Russia's Churkin.
The final watered-down draft that was voted on and defeated demanded that Syria immediately end violence, allow fundamental rights and freedoms, lift all media restrictions and allow unhindered access for human rights investigators.
It expressed the council's intention to review Syria's implementation of these demands within 30 days, and "to consider its options, including measures under Article 41 of the Charter of the United Nations."
Article 41 authorises the council to impose non-military measures which can include economic and diplomatic sanctions.
The draft also would have strongly condemned "the continued grave and systematic human rights violations and the use of force against civilians by the Syrian authorities" and called on all states "to exercise vigilance and restraint" in supplying weapons to Syria.