Syrian opposition fighters were attacked by ISIS militants north of Aleppo, near the future ISIS-free safe zone planned by Turkey and the United States, to some ground control to the rebels.
Dozens of fighters were reported dead during clashes in and around the town of Marea, 20 kilometres south of the Turkish border after suicide bombers detonated four car bombs overnight.
The assault on Marea took place after ISIS militants captured the opposition-controlled village of Um Hosh, the Syrian Observatory for Human Rights (SOHR) reported.
An opposition leader who declined to be identified due to security reasons stated that this ISIS attack was the fiercest in several months.
"There is fierce fighting," he said, "the situation in northern Aleppo is bad."
Twenty-five opposition fighters and eight ISIS militants were reported dead in Marea by the SOHR, a UK-based group that reports on the Syrian crisis via sources on the ground.
The Al Qaeda-affiliated Nusra Front announced on Monday its retreat from front-line positions against ISIS militants in northern Aleppo, relinquishing its power in that area to other opposition fighting factions, where Turkey seeks to establish a safe zone.
Last month, both US and Turkey announced their plan to drive ISIS militants out of a 110-kilometre long strip of Syrian land along the Turkish border creating a “safe zone” where refugees could settle in and the Free Syrian Army will be deployed to, which also prevents the formation of a Kurdish state on Syrian lands.
People’s Protection Units (YPG), which is the militant wing of the PYD, seek to further expand their control over Syrian territories, as a plan to form a separate Kurdish state, that already stretches to about 400 kilometres along the Turkish border, including territories that were seized from ISIS militants last year.
The soon-to-be safe zone would block ISIS only remaining access to the Turkish border.