Missiles rained down on rebel-held areas of Syria's Aleppo on Friday, causing widespread destruction that overwhelmed rescue teams, as the army prepared a ground offensive to retake the city.

Forty-five civilians including several children were killed and dozens wounded in the raids on eastern Aleppo by Russian warplanes and regime aircraft, said the Syrian Observatory for Human Rights, a Britain-based monitoring group.

The intensity of the bombardment, which included artillery barrages and barrel bombings by helicopters, brought new misery to the estimated 250,000 civilians besieged by the army.

The escalation came after US Secretary of State John Kerry failed to reach an agreement with Russian counterpart Sergei Lavrov on Thursday on terms to salvage a failed ceasefire.

The two met again on Friday at the United Nations and made what Kerry said was "a little bit of progress" on resolving their differences on Syria.

"We're evaluating some mutual ideas in a constructive way, period," Kerry told reporters.

Source : AFP