MOSCOW, Feb. 3 (Xinhua) -- A Russian military adviser has been killed by mortar shelling from terrorists in Syria, local media reported on Wednesday, citing the Defense Ministry.

"On Feb. 1, in a mortar attack by Islamic State terrorist group on a military garrison deployed at one Syrian army compound, the officer was fatally wounded," RIA Novosti news agency quoted the ministry as saying.

"The Russian military advisor went to Syria under the task of assisting the Syrian army in the development of new weapons supplied under existing contracts of interstate military-technical cooperation," the report said.

It said the officer was posthumously awarded, but didn't identify him or specify where the attack took place.

The military adviser is the third Russian officer to have been killed since Moscow began airstrikes against targets of the Islamic State in Syria in late September.

Moscow said the airstrikes came at the request of Syrian President Bashar al-Assad, with Russian aircraft deployed at Hmeimim airbase in the war-torn country.