After overrunning the air force academy at Camp Speicher where thousands of cadets were being trained, the Sunni extremists of IS separated out the Shiites and Christians among them and gunned them down one by one before dumping their bodies in mass graves or in the nearby Tigris River.

The interior ministry identified the suspect as Abdelkhalek Khazaal Soltan and said he had been arrested in a joint operation by the federal intelligence services and counter-terrorism police in Sulaimaniyah, second city of Iraq's autonomous Kurdish region.

Ministry spokesman General Saad Maan alleged that after joining IS in 2013, Soltan "took part in several operations targeting the security forces... and participated in the Camp Speicher massacre of which he was one of the perpetrators".

The massacre sparked a wave of revulsion around the world and prompted thousands of Shiite volunteers to join the fightback against the jihadists which culminated in a victory declaration in December 2017.

In a 2021 report to the Security Council, UN investigators found that the massacre of the "predominantly Shia unarmed air cadets" and their instructors involved the "war crimes of murder, torture, cruel treatment and outrages upon personal dignity".

It also found that a video of the killings released by IS in July 2015 constituted a "direct and public incitement to commit genocide against Shia Muslims".

The Iraqi courts have handed down dozens of death sentences against those convicted of taking part in the massacre.

In January, 14 people were sentenced to death for their part in the massacre. In 2016, Iraq hanged 36 men convicted of carrying out the killings.