Countless Syrians from the eastern city of Deir Ezzor have been displaced and killed in the war against the Daesh and the regime.
"With help from the Russian Air Force, the Syrian army is now completing the encirclement and destruction of a large Daesh force, numbering about 1,500 fighters, which invaded from Iraq, in the eastern part of Dayr al-Zawr", added the statement.
More than 70% of the civilian were killed in the air strikes inflicted by the Syrian regime or the Russians or the global coalition, say the defenders.
Syrian government forces and allied militia recovered Qaryatayn from Daesh some six months ago.
A US -led global coalition has been providing air support to a Kurdish-Arab alliance, the Syrian Democratic Forces, also fighting the jihadis in their former northern bastion of Raqa city and in Deir Ezzor.
Observatory chief Rami Abdel Rahman attributed the high number of deaths in the month to the "intensified air raids of the global coalition and Russia against jihadist bastions in the north and east of Syria, but also due to increased Russian and regime strikes on rebel-held areas".
It said 738 members - from Daesh and a group led by Al-Qaeda's former Syria affiliate - also died.
The Syrian Observatory for Human Rights on October 1 said 955 of the deaths were civilians, including 207 children and 148 women, according to RFE/RL.
Turkey, Iran and Russian Federation to create a "de-escalation" zone in Idlib.
Backed by Russian air strikes, the forces of Syria's President Bashar Al Assad are pressing a battle to retake Daish-controlled areas in the eastern province of Deir Ezzor.
The Russian Defense Ministry reported Saturday that Daesh and al-Nusra have borne their heaviest losses over the last few months. They were freed 25 days later.
Earlier this week, the jihadis launched an assault on government positions in Syria's vast Badiya desert, killing at least 128 regime troops.
There was no comment from the Syrian army on the report that Qaryatayn, 120 km (70 miles) northeast of Damascus, had fallen.