Syrian government airstrikes and shelling attacks on rebel-held areas killed 40 people on Monday, hours before peace envoy Lakhdar Brahimi was to brief the UN Security Council on talks with Syrian President Bashar Assad and the opposition.
At least 13 people died in the northern city of Aleppo, activists said. Video posted online showed men trying to pull victims from under the rubble of two buildings destroyed in airstrikes on the central Maadi area in Syria's biggest city.
Three children from one family were among those killed in Maadi. The Britain-based Syrian Observatory for Human Rights said government forces also shelled rebel holdouts in the central province of Homs, Idlib in the north, Daraa in the south and on the outskirts of Damascus. Troops also fought rebels in the Kaboon neighborhood in the capital.
Divisions at the UN Security Council have prevented passage of Western-backed resolutions condemning Assad and threatening sanctions if he failed to stop the violence. Russia and China have vetoed three such resolutions.
More than 20,000 people have been killed in the uprising against Assad, which started in March 2011 with peaceful street protests and gradually became a civil war.
The Syria government has in recent weeks said the rebels will soon be defeated.
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