Fierce air strikes on Aleppo after Syrian army declares offensive

People inspect a damaged site after airstrikes on the rebel held al-Qaterji neighbourhood of Aleppo, Syria

Warplanes launched some of the heaviest air strikes yet on rebel-held areas of Aleppo on Friday after the Russian-backed Syrian army declared an offensive to fully capture Syria's biggest city, killing off any hope of reviving a ceasefire.

Residents said the streets were deserted as the 250,000 people still trapped in the besieged opposition-held sector of Aleppo sought shelter from jets. The army said the operation would include a ground attack, and could last "for some time".