The Russian Defense Ministry says four of its servicemen have lost their lives after foreign-sponsored Takfiri militants launched an attack against an artillery battery of the Syrian army in the country’s eastern province of Dayr al-Zawr.

The ministry said in a statement on Sunday that two Russian military advisers, who directed the fire of the Syrian battery, were killed on the spot, while five more sustained injuries and were taken to a Russian military hospital to receive treatment.

Two servicemen succumbed to their grave injuries shortly afterwards.

The statement added that some 43 militants were killed in the ensuing clashes, which lasted for around an hour, without saying exactly when or where the fighting occurred.

The so-called Syrian Observatory for Human Rights later claimed that nine Russian soldiers alongside at least 26 Syrian army troopers had been killed in the Wednesday attack.

Observatory head Rami Abdel Rahman told AFP "several groups" of militants had attacked Syrian government forces near the town of Mayadin, located about 44 kilometers southeast of the provincial capital city of Dayr al-Zawr, and that some Russian nationals were with them at the time.

A group of Russian private military contractors, who were helping Syrian and Russian forces in the drive against Takfiri terrorists in Dayr al-Zawr, were killed in early February when they came under attack by US forces.

On October 3, 2017, Russia's Defense Ministry denied that two Russian soldiers had been captured by the Daesh Takfiri terrorists in Syria.

“There have been no incidents involving the capture or losses among military servicemen of Russia's armed forces in the province of Dayr al-Zawr or in other areas in Syria,” Russia’s Interfax news agency quoted a defense ministry official as saying at the time.

Captain Nikolay Afanasov was killed on July 12 last year by "sudden mortar fire on a Syrian government army camp" in Syria’s western-central province of Hama.

He was part of a group of military instructors who were training Syrian soldiers.

Syria has been gripped by foreign-backed militancy since March 2011. The Syrian government says the Israeli regime and its Western and regional allies are aiding Takfiri terrorist groups that are wreaking havoc in the country.

Russia has been helping Syrian forces in an ongoing battle in the province of Dayr al-Zawr as Daesh struggles to keep its last positions in eastern Syria.

The Russian military assistance, which began in September 2015 at the official request of the Syrian government, has proved effective as Syrians continue to recapture key areas from Daesh and other terrorist groups across the country with the backing of Russian air cover.

On May 21, the General Command of the Syrian Army and Armed Forces announced in a statement that complete security was restored to Damascus and its countryside after al-Hajar al-Aswad district and al-Yarmouk camp had been totally purged of Daesh terrorists.

The development was preceded by flushing the Takfiris out of the towns of Yalda, Babbila and Beit Sahem on the southern outskirts of Damascus.