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 come 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.