BEIRUT (Reuters) - Islamic State has launched a new offensive 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.
Dozens of combatants have been reported 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 most fierce 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.
Late last month, the United States and Turkey announced their intention to provide air cover for rebels and jointly sweep Islamic State from a strip of land near the border.
The envisioned buffer would deny Islamic State its last remaining access to the frontier with Turkey after a string of defeats by the Kurdish YPG militia drove it from border positions further east.
In a statement dated Tuesday, Islamic State said its fighters had attacked two buildings in Marea and killed nearly 50 members of an "apostate" militia that opposes it.
The rebel commander said the targeted rebels were from a group operating under the banner of the "Free Syrian Army".
The al Qaeda-linked Nusra Front, an enemy of Islamic State, on Monday announced its withdrawal from frontline positions against the group north of the city of Aleppo. The group criticized Turkey's plan to create a buffer, saying it served Turkey's interests rather than the fight against President Bashar al-Assad.
Thought it opposes Islamic State, the Nusra Front last month attacked rebels trained as part of a U.S.-led program to bolster insurgents viewed as moderate enough to fight the ultra-hardline group. Nusra said the U.S.-trained rebels were working for American interests.
Islamic State, which controls wide areas of Iraq and Syria, has also launched a new attack against Syrian government forces stationed at an air base east of Aleppo in recent days.
(Writing by Tom Perry; Editing by Andrew Roche)