The United States is pressing for UN Security Council condemnation of heightened attacks in Syria in a move that could reopen divisions over the war, diplomats said Wednesday.
US diplomats have proposed a draft council statement that would express "outrage" over government air strikes on the city of Aleppo.
Russia, the main international defender of President Bashar al-Assad, did not immediately comment on the statement that needs the agreement of all 15 council members to be adopted.
A number of diplomatic initiatives on Syria, including calls for a Security Council resolution on the humanitarian crisis, are on hold while waiting to see if a peace conference scheduled for January can make a breakthrough.
Security Council members "expressed their deep concern at the escalating level of violence in the Syrian conflict and condemned all violence by all parties," says the proposed US statement, a copy of which was obtained by AFP.
"They expressed outrage at the use of airstrikes by the Syrian government, in particular the use of heavy indiscriminate weapons, including Scud missiles and 'barrel bombs,' which were dropped on Aleppo between December 15 and 18, leaving more than 100 dead, many of whom were children," it adds.
Doctors Without Borders said at least 189 people have been killed and nearly 900 wounded in Aleppo since Sunday.
The statement also calls on all sides in the conflict, "in particular the Syrian government," to abide by an October 2 council statement that called for unhindered humanitarian access in the country.
The United Nations says about 126,000 people have been killed since an uprising against Assad started in March 2011 and that almost three million people have now fled to other countries.
Aid agencies say hundreds of thousands of people are in areas cut off from the outside world.
Russia's UN mission declined to make a comment on the US draft statement. Diplomats predicted it would demand changes, however.
Russia was one of 13 countries to vote against a UN General Assembly resolution earlier that blasted the Syrian government's rights abuses in the war.
The assembly resolutions cannot be vetoed, unlike the Security Council, which has been bitterly divided over the Syria conflict. Russia and China vetoed three Western-proposed resolutions seeking to increase pressure on Assad.
The council has only united to pass a resolution in September ordering the destruction of Syria's chemical weapons. Council statements, such as that proposed by the United States, are not legally binding.
Arab states in particular want the Security Council to take a tougher line over Syria.
Saudi Arabia is a key backer of the Syrian opposition and has taken a key role in drawing up a resolution demanding humanitarian access.
But diplomats say Arab nations are holding back from pressing for a Security Council vote because of the looming peace conference in Switzerland starting January 22.
"They do not want to risk a Russian veto that would expose divisions ahead of the Geneva conference," said one UN diplomat.