This file photo shows Takfiri Daesh terrorists in an unknown location in Iraq.
Daesh leaders in Mosul have executed 58 people, accusing them of trying to switch sides and hand over the city to government forces which are preparing for an imminent offensive, a report says.
Residents and Iraqi security officials, quoted by the Reuters news agency said the plot was uncovered last week and the plotters were killed by drowning while their bodies were buried in a mass grave.
Hisham al-Hashimi, a consultant to the Baghdad government on the anti-Daesh campaign, said the defectors had been arrested after one of them was caught with a message on his phone mentioning a transfer of weapons.
He later confessed that weapons had been hidden in three houses to be used in a rebellion against Daesh and to support the Iraqi army when it launches the offensive on Mosul.
Daesh members later attacked the three locations on October 4 and uncovered the stashes, Hashimi said.
Residents said a list with the names of the executed people was given to a hospital to have their families informed. Among them was a local aide of Daesh leader Abu Bakr al-Baghdadi, who led the plotters, 
“The relatives of some of those executed sent old women to ask about the bodies. Daesh rebuked them and told them ‘no bodies, no graves, those traitors are apostates,’” a Mosul dweller said.
Signs of cracks inside the "caliphate" appeared this year as the Takfiri group was forced out of half the territory it overran two years ago in northern and western Iraq.
Some people in Mosul have been expressing their refusal of Daesh's harsh rules by spray-painting the letter M, for the Arabic word that means resistance, on city walls, or "wanted" on houses of its militants. Such activity is punished by death.
Iraqi counter-terrorism service spokesman Sabah al-Numani said, “This is a clear sign that the terrorist organization has started to lose support not only from the population, but even from its own members.”
The Iraqi army and pro-government forces have been preparing for months for the assault on Daesh in Mosul.
In a move that has angered the government in Baghdad, Turkey has said it also plans to have its military forces take part in the operation to free the Iraqi city.
The prospect risks igniting a military confrontation between the militaries of Iraq and Turkey at a time when Iraqi forces should be focused on the counter-terrorism operation