Syrian government forces stepped up their attack against rebel strongholds north of the capital Damascus on Saturday, while opposition fighters declared their own offensive in the country’s largest city Aleppo.

Both sides intensified operations as an 11-nation group that includes the U.S., dubbed the Friends of Syria, began meeting in Qatar to discuss how to coordinate military and other aid to the rebels seeking to oust Syrian President Bashar Assad.

The Britain-based Syrian Observatory for Human Rights, which relies on an extensive network of activists in Syria, said the shelling of the district of Qaboun has killed three children, including two from the same family, since Friday.

Activists reported heavy shelling on many fronts on districts north of Damascus, apparently an attempt to cut links between rebel-held districts that have served as launching pads for operations against the capital.

The Lebanese TV station Al-Mayadeen, which had a reporter embedded with Syrian government forces in the offensive, quoted a military official as saying that the operation aims to cut rebel supply lines, separate one group from another, and secure the northern entrances to the capital. The regime’s forces have struggled for months to regain control of these suburbs.

The Observatory said the neighbourhood was being attacked from several different sides, while the shelling has caused structural damage and started fires. Activists from Qaboun posted on Facebook that government forces had brought up new tanks to reinforce its positions outside the neighbourhood, and the bombardment had brought buildings down.

The Observatory said rebels targeted a police academy in the nearby Barzeh area Saturday, pushing back against a government attempt to storm the neighbourhood. One rebel was killed in overnight fighting, it said.

A recent declaration by the U.S. that it had conclusive evidence that President Bashar Assad’s regime used chemical weapons on a small scale against opposition forces prompted Washington to authorize the arming of rebels, a major shift in policy. The decision also followed advances by the government forces aided by fighters from Lebanon’s Hezbollah.

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