The majority Christian town has been under Islamic State (IS) control since August last year.
- 250,000+ dead in four-and-a-half years of armed conflict
- Began with anti-government protests before escalating into a full-scale civil war.
- 11 million others have been forced from their homes
According to website RT the taking of Al-Qaryatayn would come as a major loss to IS because of its key location along Damascus-Homs highway.
It is thought that social media reports are showing that some army units have captured at least five neighborhoods on the city border.
After IS captured the town last August around 230 civilians, including at least 60 Christians went missing.
Fighting: forces loyal to President Bashar al-Assad and those opposed to his rule, as well as jihadist militants from Islamic StateThe offensive follows the liberation of Palmyra, a world heritigate site.
The terror group also released images showing their demolition of 1,500 years old Monastery of St. Elian.
The offensive on Al-Qaryatayn comes just days after Syrian state media said a mass grave has been found in Palmyra.
The city has been under Islamic State control - but was recently re-captured by Syrian troops.
It was reported that the grave contained more than 40 bodies, including many and children.