Syria's official SANA news agency on Sunday slammed the U.S. drones flying in the airspace above the region, saying the mission is a cowardly and terrorist act that infringes upon the region's sovereignty.

"Horrible violations are being committed against individuals and countries (in the region) by those drones," said SANA.

According to the report, a recent survey showed that about 2, 300 people had been killed by the U.S. drones, most of them in Afghanistan, Pakistan, Somalia and Yemen.

The report urged the UN to step up measures in line with its responsibility of upholding world peace and security.

The news agency did not give any details about a recent account claiming the U.S. drones have entered Syria to monitor the Syrian army's movement in some residential areas, mostly in central Homs province.

The American NBC News has reported that "a good number" of unmanned U.S. military and intelligence drones were operating in the sky above Syria, monitoring the Syrian military's operations on the oppositions and civilians.