The jihadists "attacked a site where... regime forces were stationed," the Syrian Observatory for Human Right said, adding that a lieutenant colonel and two soldiers died.

The Syrian army had sent forces to the area, where IS attacks are common, ahead of an expected wider sweep, said the Britain-based Observatory which has a network of sources inside the country.

In an attack on May 3, IS fighters killed at least 15 Syrian pro-government fighters when they targeted three military positions in the desert, the Observatory had reported.

IS overran large swathes of Syria and Iraq in 2014, proclaiming a so-called caliphate and launching a reign of terror.

It was defeated territorially in Syria in 2019, but its remnants still carry out deadly attacks, particularly against pro-government forces and Kurdish-led fighters in Badia desert.

Syria's war has claimed more than half a million lives and displaced millions more since it erupted in March 2011 with Damascus's brutal repression of anti-government protests.