Islamic State has launched a new attack against Syrian rebels north of Aleppo, gaining ground near the Turkish-Syrian border in an area where Turkey and the United States aim to create an area free of the jihadist group, Reuters reports.

Dozens of combatants have been reportedly killed on both sides during fighting in and around the town of Marea, 20 km (12 miles) south of the border with Turkey, where Islamic State suicide attackers detonated four car bombs overnight.

The attack on Marea followed the capture of a nearby rebel-held village, Um Hosh, by Islamic State fighters, the Syrian Observatory for Human Rights and a rebel commander said.

The rebel commander said it was the fiercest Islamic State attack in the area in several months. "There is fierce fighting," he added, declining to be identified for security reasons. "The situation in northern Aleppo is bad."

The Observatory, a UK-based group that reports on the war using sources on the ground, said at least 25 rebels and eight Islamic State fighters were killed in Marea.