Fighter jets have bombed eastern areas of Syria's second city Aleppo, a BBC reporter near the city says.

The attack is seen as a significant escalation in the conflict.

Rebels launched an offensive against Aleppo at the weekend in an attempt to wrest control of the city from government forces.
Helicopter gunships were reportedly involved in the clashes in Aleppo earlier on Tuesday.

Fierce fighting has been reported close to the historic Old City.

Pro-government troops bombarded the city, Syria's commercial centre, with shells and rocket fire as the government attempted to take back districts seized by the rebels.