The Islamic State (IS) group executed at least 24 civilians after seizing a village in northern Syria from a Kurdish-Arab alliance, a human rights monitor said on Friday.

"Isis has executed at least 24 civilians in the last 24 hours," after seizing the village of Buyir close to the northern town of Manbij, the Syrian Observatory for Human Rights (SOHR) said in a statement. The IS also took control of Qarat, al-Bwer, al-Jamosia, Qatweran, and other villages from the Syrian Democratic Forces (SDF), which is backed by the United States.

The reasons behind the execution are not clear yet.

The group, also known as the Islamic State of Iraq and Syria (Isis) or the Islamic State of Iraq and the Levant (Isil), is better known by its Arabic Acronym Daesh in the Middle East.

Daesh has been seeing several setbacks on quite a few of its fronts, increasingly losing ground to the SDF. Its fighters have been reported fleeing these places, sometimes dressed as women.

Syria's five-year war has killed more than 280,000 people and displaced millions.