Jihadist group Ahrar al-Sham is emerging from the shadows of the larger rebel outfit Al-Nusra Front as key player in northern Syria, playing up its nationalist roots and more moderate form of Islam.

Fighters from the group, whose name means in Arabic the "Free Men of Syria", are mainly to be found on the battlefields in the northern provinces of Idlib, Aleppo and central Hama alongside some 30 other jihadist organisations.

For a long time it was eclipsed by the hardline Al-Nusra Front which has claimed responsibility for the majority of deadly suicide bombings in Syria's nearly two-year conflict and is blacklisted by Washington as a terror outfit.

But in recent months Ahrar al-Sham has begun unleashing its fighters across the battlefronts, especially in Idlib where they played a leading role in advances around the city of Jisr al-Shughur, a reporter said.

Its fighters are also on the frontlines of the battles around the city of Idlib and further south in Maarat al-Numan.

Their victories have been trumpeted on the Internet and, rebel sources say, have been accomplished thanks to financial backing from Gulf Arab countries.

At the end of December, Ahrar al-Sham announced the creation of an Islamic front grouping a dozen of other organisations including Ansar al-Sham, Liwa al-Haq and Jamaat al-Taliaa.

On January 31 several other groups announced on a statement posted on the Internet that they had joined forces with Ahrar al-Sham to form a broader coalition dubbed "Harakat Ahrar al-Sham al-Islamiyya" (The Islamic Movement of Ahrar al-Sham).

Although some Arab jihadists fight amongst their ranks, most of Ahrar al-Sham's fighters are Syrian nationals while the group's founders, according to a source close to it, were former political prisoners released in an amnesty.

"The founders of the movement are all former political prisoners who were detained in the infamous Sednaya prison near Damascus," the source said.

"For years they lived and suffered together in jail (but) were set free as part of an amnesty ordered by the regime in May 2011."

The group appears to be well-structured although the names of their commanders are not in the public domain. However, a fighter known as Abu Anas is the leader for battlegrounds in northern Syria.

One of Ahrar al-Sham's strengths is that it has deep roots in northern rebel-held territory, where unlike the shadowy Al-Nusra Front, its men enjoy grassroots support because some are from the villages and cities of the region.

The group's approach to Islam is less rigid that the position of Al-Nusra Front -- which Washington says has links to Al-Qaeda in Iraq -- with group leaders insisting they oppose "fanaticism."

Ahrar al-Sham supports the creation of an Islamic state in Syria but one that is based on sharia, Islamic law that would guarantee the rights of minorities including Christians.

"Their rhetoric is loaded with Islamic references but... deep down their goal is to restore the sovereignty of the Syrian people and do away with dictatorship," said Jean-Pierre Filiu, an expert on jihadist movements.

On the ground Ahrar al-Sham fight sometimes alongside the mainstream rebel Free Syrian Army and Al-Nusra, joining in attacks on regime military targets -- but apparently refrain from taking part in suicide bombings.

Like other jihadists their fighters wear black turbans and their beards long, and fly a white flag with an eagle soaring over the name of the group on their checkpoints.