Islamic State group jihadists killed nine Syrian government troops and militiamen in an attack on military posts in the eastern desert, the Syrian Observatory for Human Rights said Tuesday.

"IS cells carried out a surprise attack, targeting positions of the regime army and National Defence Forces in the western countryside of Deir-Ezzor, killing nine of them and wounding more than 20," the Britain-based war monitor said.

The Monday evening attack triggered a prolonged gunbattle which continued until dawn Tuesday.

IS stole a military vehicle and destroyed three others before withdrawing from the area, the Observatory said.

The jihadist group continues to mount attacks on troops and other government targets from desert hideouts where its fighters regrouped after losing their last patch of territory in Syria in March 2019.