DAMASCUS, May 27 (Xinhua) -- The Syrian army has foiled an attack Wednesday by the Islamic State (IS) group on a Syrian military site in eastern province of Deir al-Zour, killing 43 IS militants, state news agency SANA reported on Sunday.

The IS militants targeted the Syrian military position near the city of al-Mayadeen in the southern countryside of Deir al-Zour, said the report.

According to Russia's Defense Ministry on Sunday, Russian military experts were present in the base at the time of the assault.

Four Russian experts were killed and three others were wounded during the sudden IS attack, which was later completely thwarted, said SANA.

Meanwhile, a source familiar with the situation told Xinhua the attack was pulled off by IS in the Faida area, some 60 km south of the al-Mayadeen city. Totally 13 pro-government fighters were killed as well.

The IS has lost large swathes of areas in Deir al-Zour to the Syrian army and controls only a few pockets in the countryside of that oil-rich province.

The US-backed Syrian Democratic Forces (SDF) has recently waged an offensive to defeat IS in areas on the eastern bank of the Euphrates River.