Moscow, Sep 25 (IANS): A Russian lieutenant general was killed in a shelling launched by Islamic State (IS) militants in northeastern Syria, the Russian Defense Ministry said on Sunday.

"As a result of the sudden IS mortar shelling, Lt. Gen. Valery Asapov sustained a fatal injury," Xinhua cited a ministry statement as saying.

According to the document, Asapov was a member of the group of Russian military advisers working with Syrian commanders during the operation aimed at the the liberation of Deir al-Zour.

The deceased serviceman will receive a state award posthumously, the statement said.

On Thursday, the ministry said that the Syrian government troops continued their offensive operations to destroy the last stronghold of the IS in the vicinity of Deir al-Zour, after breaking a three-year blockade of the city earlier this month.

About 85 per cent of the city is free from the IS and the whole city could be liberated within a week, it added.