Russia's military says two of its airmen have died in Syria after their helicopter was shot down in Syria by ISIL fighters.

Footage has emerged appearing to show the moment the helicopter was brought down.

It circles in the air several times, just missing another chopper before crashing to the ground.

A Defence Ministry statement reported by the state news agency Tass said the incident occurred on Friday east of the ancient city of Palmyra.

According to the statement, the two Russians were making a test flight in the Homs region with a Syrian Mi-25 helicopter that was carrying ammunition. It said ISIL fighters broke through Syrian forces' lines east of Palmyra at the same time.

The statement said the Syrians requested the crew help strike the ISIL fighters and the helicopter was shot down after the crew exhausted its ammunition and it was leaving the scene.

According to RT, a Russian military source told Russia's Interfax news agency the helicopter was shot down by a US produced TOW antitank missile system.