Finnish police have arrested twin brothers on suspicion of killing 11 people during a 2014 massacre in Iraq claimed by the Islamic State group, officials said on Thursday.

The pair, 23-year-old twins from Iraq, were arrested on Tuesday near Forssa, a town in southwestern Finland. They arrived in the country in September, but police would not confirm whether they had sought asylum.

"The men are suspected of murdering by gunfire 11 unarmed and defenceless prisoners," the National Bureau of Investigation (NBI) said in a statement.

The incident allegedly took place during a massacre in the Iraqi city of Tikrit in June 2014 as clashes raged between IS militants and Iraqi troops, according to police.

Police said they tracked the men down in cooperation with the Finnish Security Intelligence Service, without elaborating.

In footage of the 2014 killings, the two brothers "were not masked," NBI Chief Inspector Jari Räty told Finnish public broadcaster, YLE.

"The victims were lying on the ground and they were shot one by one," he said.

In July 2015, the jihadist group released footage of the massacre in which it executed hundreds of mostly-Shiite military recruits captured at the Speicher military base in Tikrit, the hometown of the late Iraqi leader Saddam Hussein.

The highest estimates put the number of executed cadets at 1,700.
Source: AFP