The ministry also confirmed the death of three senior ISIS commanders including Omar al-Shishani as a result of an earlier Russian strike.
Only al-Mayadeen and Bukamal remain under the IS stronghold in the southeastern countryside of Deir al-Zour, on the border with Iraq.
The report also suggested that Syrian government troops, backed by Russian warplanes, are now near the al-Mayadeen Market and Grain Silos.
In its support for Syria's brutal regime, Russian Federation has never made clear where it draws the line between groups such as ISIS and militant opposition against President Bashar al-Assad. Three children and three women were among those killed, the group said Friday, blaming IS for the attack. Both the Observatory and DeirEzzor 24 also reported that an airstrike hit the village of Mehkan, just south of Mayadeen, and said it killed several families. The ministry said the helicopter was not fired upon.More news: Trump Focuses on Bravery of Responders During Las Vegas Visit
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Also on Friday, the Russian military accused the United States of turning a blind eye and effectively providing cover to the Islamic State group's operations in an area in Syria that is under USA control.
"The main obstacle to completing the annihilation of ISIS in Syria seems to be not the fighting ability of the terrorists themselves but the support and dalliance with their American colleagues", the ministry's spokesman Igor Konashenkov said in his briefing on Wednesday, state news agency Itar-Tass reported.
According to the Russian Defense Ministry, attacks against the Syrian army have repeatedly been carried out from the 50-kilometer zone around al-Tanf on the Syrian-Jordanian border where the "US military mission" is located.
The Russian accusations likely reflect rising tensions as USA -backed Syrian forces and the Russian-backed Syrian army both of which are battling IS race for control of oil and gas-rich areas of eastern Syria.
Assad and his allies in Moscow and Tehran have now turned their attention to the eastern Syrian cities of Mayadeen and Deir Ezzor in a bid to remove ISIS from the territory that the group has held since its rise in mid-2014.