A Russian Mi-28N attack helicopter crashed in Syria in the early hours of Tuesday, killing the two pilots on board, news agency Interfax reported, citing the Defence Ministry in Moscow.
Citing a report from the crash site, the ministry said the helicopter had not been shot down, Russian state news agency TASS reported.
The helicopter came down in the central province Homs, a ministry spokesman told Interfax.
"A group of experts is working at the crash site," he said, adding that the bodies of the two pilots had been recovered and brought to a Russian air base.
Russia has been a key ally to Syrian President Bashar al-Assad since it launched an air campaign in his support in late September 2015.