CAIRO - Clashes between supporters and opponents of ousted President Mohamed Morsi on Friday killed at least 19 people and injured over 700 across the country, with violence continuing into the early hours of Saturday.

Police arrested 53 Morsi-supporters who were carrying guns, Molotov cocktails and other weapons, according to official news agency MENA.

Protesters chant slogans as they gather for a mass protest to support ousted President Mohamed Morsi in Cairo July 26, 2013. [Photo/Xinhua]

In the capital, tens of thousands of Egyptians gathered at downtown Cairo's Tahrir Square and around the presidential palace in Heliopolis to show their support for the military which has played a central role in removing Morsi from power.

Similar gatherings of Morsi-opponents were also staged in various cities across the country.

Meanwhile, loyalists of the deposed president rallied in Nasr City's Rabia al-Adawiya Square, Giza's Nahda Square near Cairo University and in some other provinces.

The number of pro-military protesters nationwide was estimated at 29 million, based on data collected by satellites and military helicopters, official news agency MENA quoted a security source as saying.

In Cairo's Shubra district, sporadic clashes left at least over a dozen people injured, with some of them suffering gunshot wounds. Elsewhere in the governorates of Gharbiya and Damietta, clashes between the two sides injured at least 18.

In contrast to relative calmness in Cairo, Alexandria has seen a much violent confrontation between the two rival groups. At least five people were killed and over 100 were injured, mostly wounded by gunshots and birdshots, according to a local hospital manager.

Similar clashes erupted in Luxor and Fayoum governorates and lasted into the early hours of Saturday, leaving at least 16 injured. Two vehicles belonged to Muslim Brotherhood members were burned.

Earlier on Friday, an investigating judge ordered detention of ousted Morsi for 15 days over charges of spying and jailbreak in 2011, during the popular uprising that toppled ex-president Hosni Mubarak.