The killings of the men, who wanted to join anti-IS paramilitary forces known as Popular Mobilisation units, took place in the town of Hawijah, a police intelligence officer and two local officials told Middle East Online.
A gruesome series of photos posted online and shared on social media are evidence that they took place.
Captions under the photos said the men were members of the Popular Mobilisation units.
This gruesome execution occurring when Security forces backed by militia are battling to regain Tikrit and neighboring area in 2 provinces.
The Popular Mobilisation units which are dominated by Shiite militia groups but also include other volunteers, including Sunnis have played a key role in the anti-ISIS fight.
Meanwhile Kurdish forces attacked ISIS positions around the oil-rich city of Kirkuk in northern Iraq at dawn on Monday, backed by heavy air strikes from a U.S.-led coalition, Washing Town Post reports
Speaking to a local television channel near the frontline, Kirkuk governor Najmaldin Karim, who was wearing a helmet, said the purpose of the offensive was to drive militants away from the city.
A Reuter’s reporter who went to the frontline on Monday said Kurdish peshmerga fighters were shelling ISIS positions and had advanced on several fronts to the west of the city, seizing villages in the Mala Abdullah and Tel Ward areas.
There was also heavy fighting between peshmerga and ISIS militants in Kharabarut, northwest of Kirkuk.
Senior member of the Iraqi National Alliance Mowaffaq al-Rubaie said today the Takfiri terrorists have planted bombs and improvised explosive devices (IEDs) throughout the city of Tikrit, the provincial capital of Salahuddin province.
"The ISIL has turned Tikrit into a booby-trapped city on the verge of blast," al-Rubaie, also a former Iraqi national security advisor, said on Monday.
After one week of heavy fighting with ISIL terrorists, the Iraqi forces have now opened their path into Tikrit, Al-Araqieh news website reported today.
The Iraqi army also continued its advances in the two towns of al-Alam and al-Dour near Tikrit in Salahuddin province, and claimed the lives of dozens of the terrorists in there.
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Iraqi troops advance near Islamic State targets in Fallujah
According to a statement released by the Iraqi Defense Ministry reported by PRESS TV At least 150 Takfiri ISIL terrorists have been killed when Iraqi fighter jets carried out two separate operations in Iraq’s violence-plagued western province of al-Anbar as well as the northern province of Salahuddin.
In Anbar Iraqi security forces killed 60 terrorists of the Islamic State of Iraq and the Levant (ISIL) group in an operation in the district of al-Qa’im in Western Anbar province.
"Security forces, backed by the Iraqi Air Force, have managed to conduct a painful strike on ISIL positions in the area of al-Qa’im," Iraq's Interior Ministry Spokesman General Officer Saad Ma’en said, FNA reported.
But The battle for the city of Tikrit is continuing to rage, with Iraqi forces trying to encircle the ISIS stronghold.