Islamic State (Isis) has executed dozens of its own fighters, a number of whom were accused of working with rival jihadist groups, in the last month, according to a UK-based monitoring group. The radical Islamists reportedly executed a total of 91 people in Syria.

The UK-based Syrian Observatory for Human Rights (SOHR), which monitors the Syrian Civil War using an extensive network of sources on the ground, revealed on Sunday that the group had killed 39 people within the group. Of the 91 executed, at least 32 were civilians, two of which were women while 11 were from rival rebels groups and nine from the Syrian military.

The 91 victims were executed for a variety of charges, including blasphemy, sorcery, adultery, banditry, sodomy, and cooperating with rival factions and the forces of Syrian President Bashar al-Assad. The Observatory said that the executions were carried out between 29 July and 29 August.

According to figures released by the monitoring group, the ultraconservative terror group has killed 1,841 civilians, of which 76 were children and 95 women, in the last year. Since the group founded its self-proclaimed caliphate, straddling the Syrian-Iraqi border, it has killed 182 of its own members who have been accused of attempting to defect from the group's ranks.

Numerous reports have emerged of foreign fighters who have joined IS wishing to return home, with the group's brutality and the poorer conditions thought to be key factors in their defections. ISIS uses beheadings as a weapon of fear both in its propaganda to the outside world and within the group.

The radical Islamist group has executed a number of western hostages and Middle Eastern prisoners in a series of horrific techniques. American journalists James Foley and Steven Sotloff were beheaded on camera last year, as were British aid workers Alan Henning and David Haines. Other videos have shown a Jordanian pilot burned alive in a cage and a number of Iraqi prisoners drowned, again in cages.

Elsewhere, IS sought to quell unrest in the western Iraqi town of Rutbah in Anbar Province on Saturday, detaining 70 people and tying dozens of residents to poles around the town to punish their protest against the group's execution of a resident of the town.