An Iraqi court Wednesday sentenced 24 men to death over the Camp Speicher massacre by the self-proclaimed Islamic State of Iraq and Sham (ISIS) terrorist group of up to 1,700 army recruits last summer.

The Central Criminal Court in Baghdad acquitted another four defendants in the case for lack of proof.

The killings were the worst of numerous atrocities during a rapid June 2014 offensive that saw ISIS seize much of northern and western Iraq as security forces collapsed.

ISIS said at the time that it had executed 1,700 Shiite soldiers who had surrendered to it after fleeing Camp Speicher, near the city of Tikrit. It said 800 Sunni troops had been "pardoned."

Photographs published by the group showed large groups of young men being rounded up, driven in the backs of trucks to fields, and then made to lie on the ground in rows as gunmen apparently opened fire on them.

A video later released showed other men being hustled to the riverside one by one, beaten, shot in the head and thrown in the water.

The camp from which the mostly young military trainees fled was never overrun by ISIS.

Human Rights Watch said in September last year that testimony from a survivor and satellite imagery confirmed the execution of 560 to 770 men, all apparently captured soldiers, at the palace complex.

The massacre led to repeated demands from the victims' families for the government to establish the fate of their sons.

Shiite militias, who spearheaded an offensive earlier this year in which pro-government forces recaptured Tikrit, have called for revenge for the killings.