MOSCOW — A firefight pitting Syrian government troops and their Russian military advisers against Islamic State militants has left at least four Russians dead and several wounded, the Defense Ministry in Moscow said on Sunday.

The firefight occurred in the Deir al-Zour governorate, an oil-rich area of eastern Syria, after several mobile units of the Islamic State attacked a Syrian Army artillery battery, the Russian news agency Interfax quoted the ministry as saying in a statement.

The fighting lasted about an hour, resulting in the deaths of 43 Islamic State fighters and in the destruction of six all-terrain vehicles, the report said. Two Russians who had been helping to direct Syrian artillery fire were killed during the fighting, the report added, and two others died later as a result of wounds sustained during the battle.

A statement circulated on the Telegram messaging app by accounts affiliated with the Islamic State said that the attack occurred overnight Wednesday near the town of Mayadeen, and that it had killed 15 men fighting on behalf of the Syrian government, including an unspecified number of Russians.