Amateur video purports to show a Syrian military helicopter exploding over the city of Idlib after being shot down by rebels.

The footage shows the aircraft spiralling downwards with smoke coming from the engines before it explodes in a ball of flames.

Outgunned rebels have previously struggled to turn the tide of the 19-month conflict against government forces equipped with tanks, jets and helicopter gunships.

However, in recent days it has appeared that rebels have acquired heavier weapons that have forced the government's air force to launch attacks from higher altitude, leading to claims of more indiscriminate bombing.