China and Russia have cast a double veto in the UN Security Council, to stop a US draft resolution calling for an end to human rights abuses in Burma.
The resolution called for the release of Aung San Suu Kyi
The two countries' ambassadors said the resolution was outside the remit of the Security Council as Burma posed no threat to international security.
US envoy Alejandro Wolff said he was "deeply disappointed" by Russia and China's first joint veto since 1972.
South Africa, a new non-permanent member, also opposed the document.
Qatar, Indonesia and the Republic of Congo abstained while the nine other members voted for.
The draft resolution urged Burma's military rulers to end persecution of minorities and opposition groups.
It called for the release of all political prisoners, including opposition leader Aung San Suu Kyi, who is currently under house arrest, and for all political groups to operate freely.
"The United States is deeply disappointed by the failure of the council to adopt this resolution," acting US ambassador Alejandro Wolff said.
Bu Russia's representative, Vitaly Churkin, said he opposed "attempts at using the Security Council to discuss issues outside the purview".
Burma released 40 political detainees last week to coincide with the 59th anniversary of independence.
Another five activists were freed on Thursday, in what pressure groups say could have been a move designed to scupper the UN resolution.
The UN estimates that there are about 1,100 political prisoners in Burma.