By Agencies

At least 400 suspected ISIL victims, many wearing prison uniforms, found buried at military base formerly used by ISIL.

Mass graves containing at least 400 suspected ISIL victims, many wearing prison uniforms, have been found in northern Iraq.

The sites were discovered on Saturday near Rashad airbase close to the group's former stronghold, Hawijah, 45km west of Kirkuk.

Iraqi forces recaptured the town of Hawijah and surrounding areas from the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group in October. It was one of their last strongholds in Iraq.

Rashad airbase, located about 30km south of Hawijah, was used by ISIL as a training camp and logistic base.

READ MORE: Investigation: ISIL buried thousands in 72 mass graves

The discovery of the mass graves was not the first after the routing of ISIL in Iraq and Syria.

In August, Iraqi military investigators discovered two mass graves near a former ISIL prison outside Mosul that contained the bodies of 500 victims.

READ MORE: Iraqi forces 'capture majority of Tal Afar' from ISIL

Earlier that month, Associated Press news agency conducted a survey that concluded that ISIL buried thousands of their victims in at least 72 mass graves across Iraq and Syria.

Through interviews, photos, and research, AP obtained locations of 17 mass graves in Syria, including one with the bodies of hundreds of members of a single tribe all but exterminated when ISIL took over their region.

Of the 72 mass graves documented in the investigation, the smallest contained three bodies; the largest is believed to hold thousands.