Britain-based Syrian Observatory for Human Rights says a car bomb exploded at makeshift base close to an oilfield in the village of Shheel in east Syria.
A car bomb on Thursday killed 20 people, including 14 oil workers, near a base used by US-backed militia battling Daesh in east Syria, a war monitor said.
“The car bomb was detonated remotely in the village of Shheel” close to an oil field acting as a base," the Britain-based Syrian Observatory for Human Rights said.
Six militants from the YPG/PKK-dominated SDF were also killed as they escorted the workers in vehicles from the Omar oil field, it said.
In its more than 30-year terror campaign against Turkey, the PKK, listed as a terrorist organisation by Turkey, the US and the EU, has been responsible for the death of some 40,000 people. YPG is its Syrian branch.
Daesh militants handed over to Iraq
Meanwhile, US-backed militia handed over to Iraq on Thursday members of Daesh who were detained in Syria.
Iraqi security forces have received from the SDF "130 Iraqi Daesh fighters," General Yehya Rassoul, a spokesman for Iraq's security media centre, told AFP.
"They used to fight in Iraq but when the battles were over they went to Syria where they were captured by SDF militants during recent fighting," he said.
Iraq declared victory over the group in late 2017 following a punishing campaign to dismantle its self-declared "caliphate" that once covered a third of the country.
Naim al Kaood, the head of the security department in Iraq's Anbar province bordering Syria, told AFP the 130 Daesh militants handed over were "wanted" by the Iraqi government.
A commander of the Hashd al Shaabi paramilitary force, who declined to be named, said the militants were all Iraqi nationals and were transferred to authorities, including members of military intelligence.
"Other groups will be handed over to Iraq, including families of the militants," said the commander.
SDF, backed by coalition air strikes, has trapped Daesh members in less than half a square kilometre (a fifth of a square mile) in the village of Baghouz, their last sliver of territory in eastern Syria.
On Wednesday, hundreds of people, including women and children, were trucked out of Baghouz.
Daesh had seized swathes of Syria and Iraq in 2014 and declared a cross-border caliphate.