Syrian opposition forces seized a strategic town from ISIL near the Turkish border north of Aleppo in another important step on the march towards the armed group's de facto capital, Raqqa.

The UK-based Syrian Observatory for Human Rights war monitor confirmed that groups fighting under the banner of the Free Syrian Army (FSA) captured the town of al-Rai on Thursday after fierce battles with ISIS.

After taking over al-Rai, fighters said they dismantled land mines surrounding civilian houses and farm lands.

The opposition forCes said their next move will be an advance on the ISIL-held city of al-Bab - south of al-Rai and northeast of Aleppo, Syria's second-largest city.

"Al-Rai is a strategic region and it's a gateway to proceed towards the regions of Jarabulus and al-Bab," a fighter from the Faylaq al-Sham group told Al Jazeera.

The recent gains by the opposition forces is a boost to Turkey, which has sought to prevent Syrian Kurdish-led forces from expanding their stretch of territory along the border.

It was the first retreat by ISIL fighters since opposition forces made major advances in the area last May and captured areas close to the Azaz border crossing with Turkey.

A sustained opposition advance near the Turkish border this week allowed moderate forces to capture a string of villages and eroded ISIL's footholds in an area identified as a priority in the fight against the group.

Opposition forces who previously struggled to make gains against ISIL in the area and had been fending off advances by Kurdish-led fighters mobilized several thousand fighters for the al-Rai attack, opposition sources said.

An alliance of FSA groups formed for the offensive includes the Turkish-backed Sultan Murad and Failaq al-Sham groups.

ISIL's foothold along the Turkish border was also significantly loosened last year by US-allied Kurdish fighters of the YPG, which gained territory from the group farther east.

PHOTO CAPTION

Children play near upright buses barricading a street, which serve as protection from snipers loyal to Bashar al-Assad, in Aleppo's opposition-controlled Bustan al-Qasr neighborhood, Syria April 6, 2016. (Reuters)

Al-Jazeera