Mustard Gas Used on Assad troops by IS

Rebels have shot down a Syrian fighter plane over the province of Aleppo.

Unconfirmed reports say militants from Nusra Front have captured one of the crew alive.

State media in Syria have accused militants from so-called Islamic State (IS) of using mustard gas against government forces in the north-east.

Troops came under fire at an air base which IS has been trying to capture in Deir al-Zour, they say.

Reuters news agency cites monitoring and rebel sources as saying the pilot was taken by the al-Qaeda-linked group after the plane crashed in countryside.

Syrian state TV said the plane had been shot down by a surface-to-air missile and a rescue operation was under way. It did not say whether the pilot had been captured.