Turkish shelling and air strikes have killed at least 20 civilians in Syria on the fifth day of an incursion against the Islamic State of Iraq and the Levant (ISIL) group and Kurdish forces, according to a monitoring group.

Sunday's deaths came a day after Turkey blamed Kurdish forces battling for control of the border region for its first fatality.

"At least 20 civilians were killed and 50 others wounded by Turkish artillery fire and air strikes on Sunday morning at Jeb el-Kussa," a village south of Jarablus, said Rami Abdel Rahman of the Syrian Observatory for Human Rights (SOHR), a Britain-based monitor with a network of sources on the ground.

Turkey has not yet released an official comment.

The SOHR said the bombardment targeted an area south of the former ISIL stronghold of Jarablus, which Turkish-led forces captured on the first day of the incursion.

Jeb el-Kussa is located 14km south of Jarablus and is controlled by fighters from the area backed by Kurdish forces.

Some of the fighters were killed in Sunday's shelling and air strikes but the number was not yet clear, said the SOHR.

On Saturday, clashes erupted for the first time between Turkish forces backed by tanks and pro-Kurdish fighters in the town of Al-Amarneh, also south of Jarablus.