Dozens of the terrorists were killed and many more wounded after the army launched an attack on the 20-meter tunnel located in the southern part of the city, sources said.
The attack came just days after the Syrian troops advanced on Daesh's strongholds in the towns of al-Mayadeen and al-Ashara in Deir ez-Zor province, where scores of additional terrorists were eradicated.
Earlier, the Syrian Army and the NDF foiled a Daesh attempt to penetrate the army's positions in the Eastern part of Deir ez-Zor military airport, killing at least five terrorists.
Syria has been mired in a civil war since 2011, with forces loyal to the country's President Bashar Assad fighting a number of opposition factions and extremist groups, including Daesh and the Al-Nusra Front, which have been blacklisted as terrorist organizations by many countries, including Russia.
Rus ASF and AF of #SYRIA didn't make strikes on opposition units, which joined ceasefire and informed Rus or US Centres about their location— Минобороны России (@mod_russia) 31 марта 2016 г.
In February 2015, the UN Security Council unanimously adopted Resolution 2268, endorsing a Russia-US agreement on the cessation of hostilities in Syria; the ceasefire came into force shortly thereafter, on February 27, and fighting throughout much of the country subsided. However, Daesh and the Al-Nusra Front were not included in the truce.
Between September 30, 2015 and March 14, 2016, the Syrian Army's anti-terror efforts were backed by an extensive Russian air campaign. During that period, more than fifty Russian warplanes, including Su-24M, Su-25 and Su-34 jets, conducted precision airstrikes on Daesh and Al-Nusra targets in Syria at the behest of President Assad.
Moscow will maintain a military presence in Syria, although a deadline for a complete pullout has not yet been announced. Putin also indicated that Russian forces will remain at the port of Tartus and Hmeymim Airbase.