Turkish shelling and air strikes killed at least 35 civilians in Syria on Sunday, the fifth day of an incursion against Islamic State group jihadists and Kurdish militia, a monitor said.

"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 Jarabulus, said Rami Abdel Rahman of the Syrian Observatory for Human Rights.

The Britain-based group said four local fighters were also killed in the bombardment.

It also reported another 15 civilians killed and 25 wounded, many seriously, in Turkish air strikes near the town of Al-Amarneh, also south of Jarabulus.

The deaths come after Turkey on Saturday suffered its first fatality since launching operation "Euphrates Shield" in Syria, blaming Kurdish militia in a fight for control of the border region.

The Observatory said the bombardment targeted an area south of the former Islamic State group stronghold of Jarabulus, which Turkish-led forces captured on the first day of the incursion.

Jeb el-Kussa is located 14 kilometres (almost nine miles) south of Jarabulus and is controlled by fighters from the area backed by Kurdish forces.

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 Jarabulus.

Turkey considers the main armed force of Syria's Kurds, the YPG, to be a branch of the Kurdistan Workers' Party, which is deems a "terrorist" organisation.

Its military intervention has further complicated a conflict that has killed more than 290,000 people and displaced more than half the country's population since March 2011.