A bus being removed from the site of a previous attack, in October 2021, in Damascus, Syria. AFP

Three Syrian policemen were killed and two wounded in an attack on a security patrol in the eastern countryside of Daraa on Thursday, a police source said.

"A group or terrorists attacked a police patrol using light weapons, and then an explosive device went off on Daraa-Gharz Prison road," the source at Daraa Police Command told the official Sana news agency.

The source said that the attack left three police dead and others wounded.

Earlier this month, a bomb planted by militants in the village of Al Yadudah, north-west of Daraa, exploded, injuring several people.

The war in Syria, which broke out in 2011, is estimated to have killed nearly half a million people and displaced millions more since it began with a brutal campaign against anti-government protests.

Daraa was once known as the "cradle of the revolution," one of the largest centres of protest early in the crisis, and was later heavily bombed by the Syrian military.

In 2018 the Syrian government and rebels in Daraa agreed to a truce that involved the insurgents handing over their weapons. But the ceasefire broke down in September last year and heavy fighting broke out again, displacing about 40,000 people.