A Giza court has upheld the death sentences on 12 supporters of ousted Islamist President Mohamed Morsi Wednesday, judicial sources said, on charges of killing a senior police officer after storming the police station.

The court also sentenced 10 people to life in prison and acquitted one other.

The verdict is in relation to violent events that followed the dispersal of two main sit-ins of ousted Islamsit President Mohamed Morsi supporters in August, 2013, where Morsi supporters were charged with attacking the police station in Kerdasa, a stronghold of Islamists, and killing Major General Nabil Farrag, deputy head of Giza security.

General prosecution had charged the defendants with forming an illegal group to disturb the rule of law, attack security forces and target public installations. Those who received death sentences were charged with murder, possession of ammunition and weapons.

Investigations showed that two of the defendants led the group, gathered in a farm on the western borders of the country and possessed large amount of weapons and ammunition to plan Kerdasa attack.

The ambush in September of last year also wounded nine officers. 

The verdict Wednesday could still be appealed.

In March, southern Egypt's Minya court sentenced 529 of Morsi supporters to death on charges of murdering a police officer. The court later upheld sentences on 37 of them and sentenced the rest to life in jail. One month after, a court, also in Minya sentenced 683 Morsi supporters to death for attacking a police station and killing a police officer.

Mass death sentences were criticised by international and local rights groups.