Amman: The powerful Syrian Islamist insurgent group Ahrar Al Sham has merged with a smaller militant faction in a move that could thwart the growing influence of Al Qaida’s offshoot in northwestern Syria, militant sources said.

Ahrar Al Sham, one of the largest militant groups in Syria alongside Daesh and Al Nusra, announced on Sunday a merger with the smaller Suqur Al Sham, which shares its strongly Islamist line.

A statement said the merger was prompted by a need to unify ranks in what some rebels say will expand Ahrar Al Sham’s clout in the northwestern province of Idlib, where its rival Al Nusra has expanded since recently crushing Western-backed non-jihadist rebel groups.

“This will present a stronger competitor for Al Nusra in Idlib. With other mergers they could get closer to...equal footing,” Abu Malek Al Shami, a local rebel commander from Jaish Al Mujahdeen Wa Al Ansar told Reuters on viber.

Islamist militant groups have been engaged in internecine fighting since the rise of ultra-hardline Daesh militants that have sought to subjugate rival groupings.

“All these factions are not entering a phase of cooperation but one of imposing their presence by force,” Abu Haniyah said.

The factionalism has helped Syrian President Bashar Al Assad’s army gain ground against his opponents and inch closer to encircling them in rebel held parts of the northern city of Aleppo.

Ahrar Al Sham draws most of its leaders and rank and file from local Syrians in contrast to Al Nusra, the local franchise of Al Qaida, which has many foreign fighters.

A blast last September killed the leader and most commanders of the group that is also part of the Saudi-backed Islamic Front alliance. That has been in armed conflict with Daesh which has seized swathes of territory in Syria and Iraq.

Ahrar Al Sham, which is widely believed to have received funding from Gulf states and has at least 10,000 fighters, aims to implement Sharia law in Syria.

It was at one point considered the strongest insurgent group in the civil war.