At least 140 people have been killed and over 4,500 others injured in heavy fighting in Egypt during rival mass rallies for and against the army overthrow of President Mohammad Mursi, who was placed under investigation for murder

At least 140 people have been killed and over 4,500 others injured in heavy fighting in Egypt during rival mass rallies for and against the army overthrow of President Mohammad Mursi, who was placed under investigation for murder, Egyptian medical and Muslim Brotherhood sources said.

The clashes broke out after Mursi's supporters gathered in Cairo’s Nasr City district on Friday, demanding his reinstatement.

Mass rallies were held in response to Muslim Brotherhood’s call for a “peaceful stand” against the recent military “coup” that toppled Mursi. In a statement on Thursday, the movement’s leader, Mohamed Badie, asked Egyptians to come to the streets and demand freedom and legitimacy.

Meanwhile, the Egyptian army reportedly used live ammunition on demonstrators during the mass rallies.

A Reuters reporter saw heavy exchanges of gunfire in the early hours of Saturday between security forces and Mursi supporters, who tore up pavement concrete to lob at police. Clouds of teargas filled the air.

Following Sisi's summoning of protests, news of the investigation against Mursi over his 2011 escape from jail signaled a clear escalation in the military's confrontation with the deposed leader and his Islamist movement.

MENA said Mursi, who has been held incommunicado at an undisclosed military facility since his overthrow, had been ordered detained for 15 days pending the inquiry.