Jihadists on the Syrian-Lebanese border have returned a Lebanese soldier who was kidnapped last month following the intervention of Qatar.

The Nusra Front handed over the soldier to a Qatari envoy who has been negotiating the release of almost two dozen soldiers who were captured in the flashpoint town of Arsal in Lebanon's Bekaa Valley.

Kamal Mohammad Hujeiri was let free by the jihadists following six hours of negotiations between the Qatari envoy and the Nusra Front and Isis (now known as the Islamic State).

It remains unclear what concessions were made by the Qatari envoy in order to secure the soldier's release.

Twenty-one Lebanese soldiers remained in the captivity of the jihadists following clashes in Arsal last month.

The Islamist militants from the Nusra Front are seeking a humanitarian corridor for its fighters in Arsal, the release of the militants detained during the Arsal clashes and that Syrian refugees do not face reprisal attacks from government forces.

Lebanon's Environment Minister Mohammad Machnouk confirmed Beirut's cabinet wanted to hold talks with militants to free the soldiers, adding Turkish, Qatari and Lebanese officials were all involved in the process to secure their release.

Last month, Nusra Front killed Lebanese soldier and hostage Mohammad Maarouf Hammieh while threatening to kill another hostage, policeman Ali Bazal, because of the lack of progress in the negotiations with the Lebanese government.

Up to 3,000 militants from IS and other jihadists occupy the mountain range between Lebanon and Syria near the Sunni town of Arsal.