Abu Hajar al-Sufi, a top lieutenant of Isis leader Abu Bakr al-Baghdadi, has been killed in a US airstrike.
Iraq's defence ministry announced the killing of al-Sufi along with two other senior Sunni insurgents in the Isis-controlled northern Iraqi city of Mosul.
One of them was said to have been an explosives expert and the other a military strategist.
Pentagon spokesperson Colonel Steve Warren could not confirm the death of the Isis commander but told NBC News that the senior figures could have been killed if they had been "inside troop formations".
Speculation in the Iraqi social media suggested that al-Baghdadi himself may have been killed in the attack but the Iraqi defence ministry clarified that it was his suspected right-hand man who was killed.
The fallout of the death of al-Sufi, if confirmed, is still unclear as analysts are yet to get a clear picture of the organisational structure of the Isis.
In another development, the Sunni insurgents are said to have abducted dozens of men in northern Iraq.
The abductions took place in Tal Ali village, about 240kms north of the capital Baghdad, reports quoting residents said.
At least 50 men were believed to have been rounded up before being loaded onto cars and trucks and taken to a secret location.
The abductions took place after the residents set Isis flags on fire as the militants were retreating in the face of the Iraqi offensive.