Russia on Wednesday blocked a British-drafted UN Security Council statement condemning the Syrian government attacks on the city of Aleppo, diplomats said.
It was the second time in a month that Russia objected to a western bid to slam President Bashar al-Assad's air assault against Syria's biggest city which has killed hundreds since December 15.
Aid groups say that Scud missiles and barrels packed with explosives and shrapnel have been dropped on schools, markets and hospitals in Syria's biggest city. They say more than 700 people have been killed.
Britain circulated a draft press statement expressing "outrage" at the government attacks on civilians to the other 14 members of the council on Tuesday night.
The statement needs the agreement of all members to be released, and Russia objected on Wednesday, insisting all references to Aleppo be taken out, diplomats said.
"They just want a general text condemning all attacks by all sides in Syria," said one diplomat involved in negotiations.
Russia is a key backer of Assad and has used its power as a permanent council member to veto three legally binding resolutions on Syria since the war started in March 2011.
The United States proposed a non-binding statement on Aleppo in December, but Russia blocked it with what western diplomats called "wrecking amendments" which would have watered it down.
The United States had doubts about releasing the new statement so close to the Syria peace conference to start in Switzerland on January 22, diplomats said.
"The Security Council cannot remain quiet on this issue," said one western diplomat of the new attempt. "The British draft is not anything that anyone should be surprised by."
"The members of the Security Council expressed outrage at the daily use of air strikes by the Syrian government against the city of Aleppo which have left over 700 dead and over 3,000 injured since December 15," said the statement, which was obtained by AFP.
It added that the attacks were a "cynical and systematic" disregard of international law banning attacks on civilians.
Russian diplomats would not immediately comment on the proposed statement.
Opposition fighters open fire taking cover from behind a car during fightings in the Salaheddin district of the northern Syrian city of Aleppo on October 9, 2013.
[Image via Agence France-Presse]