Nearly 50 airstrikes hit rebel-held areas in and around the Syrian city of Aleppo Sunday in some of the heaviest recent raids by Russian and Syrian government aircraft, residents and an activist group said.The group, the Syrian Observatory for Human Rights, also said an unidentified war plane had crashed in the countryside south of Aleppo, in an area where Islamist rebel fighters are battling the Syrian army and Iranian-backed forces.



"This weeklong campaign of bombing is very intense and day by day it's getting worse ... it is the worst we have seen in a while," said Bebars Mishal, a civil defense official in rebel-held Aleppo.



For their part, rebels hit government-held areas of Aleppo in what Syrian media said was an escalation of attacks on the western districts.



Aleppo, the country's largest city before the war, has been divided for years between rebel and government-held zones.

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