An Iraqi court has pronounced death sentences on 24 Islamic State (Isis) militants for their role in the massacre of hundreds of air force cadets in Tikrit last year.

The mass killings took place when Isis fighters overran Tikrit in June 2014 and captured the unarmed cadets outside Camp Speicher, a former US military base, near the city.

Up to 1,700 soldiers are believed to have died at the hands of the jihadist group, which posted graphic photos and videos of the massacre on the internet.

All 24 of the defendants sentenced to death were Iraqi nationals. They all pleaded not guilty to the charges of murder and membership of a terrorist group, the Associated Press news agency reported.

They told the court that their confessions were coerced under torture by Iraqi officials.

At one point in the trial, several relatives of the deceased reportedly stormed the courtroom and threw shoes and bottles at the defendants, who were locked in a cage.

Ali Abdul-Hamza, whose brother was among the victims, told AP: "Justice is done. We are relieved to see these criminals receiving the courtroom."

The sentences will not be carried out right away as they have to be approved by a higher court.

The Iraqi government was seeking another 604 suspects in connection with the incident, a judiciary spokesman was quoted as saying.

One of the worst atrocities committed by Isis since its inception, the Camp Speicher massacre drew widespread coverage in the international media.

Graphic footage released by the jihadist group in the aftermath of the killings showed the cadets being beheaded, shot and choked while the fighters celebrated.

Iraqi forces retook Tikrit in April and began exhuming the remains of the soldiers from mass graves at four different sites.