The Iraqi militant group Islamic State (Isis) has purportedly executed a top commander for masterminding an alleged coup against the self-proclaimed caliph Abu Bakr al-Baghdadi.

Local reports suggest that the execution of Abu Usman al-Hassan, one of the top administrative officials, took place in Mosul, the key IS stronghold.

"IS executed the commander inside Mosul after severe disagreements between him and a number of other commanders," an eyewitness told the Iraq Press, which first reported the story.

"He was accused of conspiring against the 'caliphate state'."

Al-Hassan, once a close aide of al-Baghdadi, was given death penalty after a short verdict, but the exact execution method remains unclear.

His death is said to be the result of multiple rifts running in the group between foreign jihadists and local militants, though it remains unverified.

Following al-Hassan's execution, a large number of Islamists, who were under his command, were either moved to Raqqa in Syria or fled Mosul.

"Subsequent to the execution of the senior leader Abu Usman Hassan, the group sent nearly 250 fighters, mostly Syrians and from other Arab nationalities, to Raqqa – IS de facto capital in Syria," a local source told the ARA News.