UNITED NATIONS — Russia objected to a proposed UN Security Council statement expressing outrage at Syrian government airstrikes, especially this week’s indiscriminate use of heavy weapons in Aleppo that have killed more than 100 people, UN diplomats said Thursday.

The statement, proposed by the United States, required approval from all 15 council members.

Diplomats said Russia, the most important ally of Syrian President Bashar Assad, wanted all references to the regime stripped from the statement so the US decided to drop it. The diplomats spoke on condition of anonymity because the statement was circulated privately.

The statement would also have condemned violence by all parties in Syria and expressed deep concern at the escalating level of violence in the Syrian conflict, including the use of Scud missiles and “barrel bombs” in Aleppo.

Russia and China, which also supports the Assad government, have vetoed three resolutions that would have pressured Assad to end the violence. They were backed by the US and its Western allies who support the opposition.

Kurtis Cooper, spokesman for the US Mission to the United Nations, said the United States is “very disappointed that a Security Council statement expressing our collective outrage at the brutal and indiscriminant tactics employed by the Syrian regime against civilians has been blocked.”

“These barrel bombs — and the explosive materials contained within them — further underscore the brutality of the Assad regime and the lengths they will go to attack and kill their own people, including women and children. … And regime air raids in and around Aleppo have continued unabated,” Cooper said. “Surely, at a minimum, the Security Council should be able to condemn such barbarities.”

Before Russia’s objection was made known, Syria’s main opposition group in exile, the Western-backed Syrian National Coalition, criticized the Security Council for considering “a mere press statement” to protest “the latest act of terror” in Aleppo. The coalition also accused the council of failing “to take any steps to eliminate the use of conventional weapons that are being used as weapons of mass destruction on a much larger scale.”

In a withering air assault this week, the Syrian government has pummeled opposition-held neighborhoods in the northern city of Aleppo, leveling apartment buildings and flooding hospitals with casualties.

Rebels say the unusually intense airstrikes in Aleppo have prompted civilians to flee to the countryside and could portend a government ground offensive against the opposition-held half of the city, which has been divided for a year and half by grueling fighting.

The government launched the campaign five weeks before peace talks are scheduled to begin on Jan. 22 in Montreaux, Switzerland, sparking speculation that Assad may be trying to strengthen his position on the ground and expose opposition weaknesses before sitting down at the negotiating table.

The proposed US statement would have welcomed the Jan. 22 conference aimed at ending the Syrian conflict and reiterated the council’s call for greater access for humanitarian workers to deliver desperately needed aid.

Copyright 2013 The Associated Press