Abu Mohammed al-Golani, leader of the Nusra Front, called on the ISIL group to agree to arbitration by their religious scholars to end more than a year of feuding which has turned violent in some areas in Syria.

Heavy clashes between the two groups and other extremist fighters in militant-held northern and eastern Syria have led to hundreds of deaths and have undermined the wider military campaign against the Syrian national army.

"We will wait for five days from the date of this recording for your formal reply," Golani said in the audio tape, released on a web site affiliated with his group.

"By God, if you reject God's ruling again and do not put an end to your plague against the Umma, then the Umma will launch an assault against this ignorant ideology and will terminate it, even from Iraq," he said.

The fighting broke out at the start of the year when several militant groups launched what appeared to be coordinated attacks on ISIL fighters, who have alienated many Syrians in the areas under their control.

Golani's Nusra Front, which has sworn allegiance to Al-Qaeda leader Ayman al-Zawahri, had until then avoided openly confronting ISIL, with which it shares a radical ideology, despite deep rivalry and tensions between the two groups.

Al-Qaeda has dissociated itself from ISIL.

In his statement, Golani differentiated between ISIL and the Western-backed Syrian opposition, both of which he described as infidel groups.

SHI/SHI