The agency's report gave no details on today's proceedings, held in a makeshift courtroom in the national police academy in eastern Cairo.
The trial is one of four the Islamist Morsi and top leaders of his Muslim Brotherhood face. The charges they face mostly carry the death penalty.
Morsi was ousted by a popularly backed military coup on July 3.
The charges against the defendants stem from violence outside the presidential palace in December 2012 when his supporters attacked protesters staging a sit-in.