The ultra-hardline Islamist group seized the town of al-Rai from factions fighting under the banner of the Free Syrian Army, part of months of back-and-forth fighting in northern Aleppo province, the Syrian Observatory for Human Rights reported.
Islamic State has declared a cross-border Islamic caliphate in Syria and neighbouring Iraq and is also battling other insurgent groups caught up in Syria's civil war, some of them backed by Turkey and Western powers.
It has made steady gains near the Azaz border crossing with Turkey since last May, but has been pushed back in a number of areas in recent months by rival rebels and Syrian government forces supported by Russian air strikes.
