Islamic State’s leadership in Mosul moved to crush the second rebellion against them in a week on Monday, Iraqi media reported, with news of mass executions as anti-IS forces advance on the town.

“Through their media arm in Mosul, IS announced that they had crushed a rebellion against Abu Bakr al-Baghdadi by the ‘Islamic police force’,” a local resident told Iraqi news site al-Sumaria on Monday.

The leader of the attempted rebellion was named as Abu Othman, a local resident of Mosul who was chief of the IS police force in the city.

Othman had reportedly led his armed forces in attacks on four sites where IS leader al-Baghdadi was thought to be hiding, a separate source told al-Sumaria.

“IS fighters killed the head of the police force along with some companions, and then carried out mass executions against dozens of members of the police force in areas where the clashes had happened.”

Reports of internal strife within IS come as Iraqi forces press an advance on Mosul, Iraq’s second biggest city which has been under IS control since 2014.

The Iraqi armed forces, which are advancing towards Mosul along with Iran-backed militias and Kurdish troops, announced on Monday afternoon that they had seized back control of three villages just southeast of the city “without resistance”.

Ahead of the announcement of the long-awaited offensive on Monday night, IS top brass in Mosul had reportedly faced down an earlier attempted rebellion in the city.

IS on Friday executed 58 people suspected of taking part in a plot against the group’s top leadership.

Residents who spoke to Reuters from some of the few locations in the city that have phone service said the plotters were killed by drowning and their bodies were buried in a mass grave in a wasteland on the outskirts of the city.

Among them was a local aide of Baghdadi, who led the plotters, according to matching accounts of five residents. The failed plot was confirmed by Hisham al-Hashimi, an expert on IS affairs who advises the government in Baghdad, and by colonel Ahmed al-Taie, from Mosul's Nineveh province command's military intelligence.

This article is available in French on Middle East Eye French edition.