The report also suggested that Syrian government troops, backed by Russian warplanes, are now near the al-Mayadeen Market and Grain Silos.
Many of them came from the former Soviet Union, Tunisia, and Egypt, according to the ministry.
Islamic State has staged fierce counter-attacks in central Syria in recent days, testing the army's control of an area seized in a months-long eastward offensive.In June, two USA intelligence officials told Reuters that they believed Islamic State had moved most of its diminished command structure and propaganda team to al-Mayadin, southeast of its former capital of Raqqa.
The ministry noted that the armed forces destroyed a command post of terrorists near Meyadin city of Syria and killed up to 80 militants, including nine militants coming from the North Caucasus.
MOSCOW, Oct. 7 (Xinhua) - About 120 Islamic State (IS) militants and more than 60 foreign mercenaries in Syria were killed in airstrikes launched by Russia over the past 24 hours, the Russian Defense Ministry said Saturday. The US military base in al-Tanf protected by a "human shield" consisting of Syrian refugees has turned into a "black hole" on the Syrian-Jordanian state border from where mobile groups of the Islamic State (IS, terror group, outlawed in Russia) carry out sabotage and terror attacks, Russian Defense Ministry Spokesman Major-General Igor Konashenkov said on Friday.
Mayadeen is one of the Daesh group's last bastions in Syria.
Hezbollah Military Media Center reported Friday that Syrian forces have retaken control of positions and heights parallel to the main road connecting al-Mayadin, located in the province Dayr al-Zawr, to the provincial capital of the same name.
The parallel offensive by the Syrian Democratic Forces (SDF), a US-backed alliance of mainly Kurdish militia, has on numerous occasions hampered the Syrian government's anti-Daesh battles.
The observatory said on Friday there were clashes in several areas in eastern Deir Ezzor province.
The advances against IS in Deir Ezzor have cost a heavy civilian death toll from Russian and coalition air raids.
Russian President Vladimir Putin said he would continue to support Assad till Syria is "completely sanitised".