A Syrian warplane belonging to Bashar al-Assad regime air power crashed northeast of Damascus on Friday. Syrian Opposition members later claimed that and al- Nusra Front members had killed the aircraft’s pilot after his capture.

Syrian state media said the crash had been caused by a technical fault and that a search was under way for the pilot, who had ejected. Insurgents said the plane had been shot down, but did not say what weaponry was used.

Anti-Assad fighting group Jaish al-Islam said the pilot had been killed by an al- Nusra Front fighter while being held at a joint command center. Jaish al-Islam had earlier said that the pilot’s body would be handed over to them since they had shot down his plane.

Jaish al-Islam, which controls territory on the Syrian capital’s eastern and northeastern outskirts, had earlier circulated a photo that it said showed the pilot.

“We call on the Nusra Front and Ahrar al-Sham to issue a statement explaining what happened and also call on them to hand over the pilot’s body,” a Jaish al-Islam statement said.

Rebels shot down at least two warplanes earlier this year. The Assad regime said one of them had been downed by an anti-aircraft missile, but Syrian opposition officials said they had used anti-aircraft guns.

U.S.-backed Syrian opposition fighters have long demanded anti-aircraft missiles to help them fight off air raids by Assad and Russian forces.

Russia has been a major ally of Syrian head of regime, Bashar al-Assad, and arms supplier in the civil war, now in its sixth year.