CAIRO — An Egyptian court official says authorities have launched a civilian investigation of the country's former military transitional rulers for their alleged role in the killing of protesters during their 18 months in power.

The official said Monday that an investigative judge was assigned to look into accusations against officers including the head of the ruling military council, Field Marshal Hussein Tantawi.

It would be the first time that Tantawi and other members of the Supreme Council of the Armed Forces are investigated for the deaths of protesters in clashes with security forces and soldiers.

It is also unprecedented for civilians to probe officers, normally protected from oversight by anyone outside the military.

The official spoke on condition of anonymity because he was not authorized to speak to reporters.