The government of Egypt has said that authorities would "strike with an iron hand all those who seek to tamper with the nation's security", after the cabinet held crisis talks about sectarian violence that left 12 people dead and hundreds injured, according to AFP.

Justice Minister Abdel Aziz al-Gindi said that the government would "immediately and firmly implement the laws that criminalise attacks against places of worship and freedom of belief", using anti-terror laws to combat those "threatening national security".

Imbaba in northwestern Cairo was the scene of the clashes between Muslims and Christians, and about 190 people have been detained in connection with the skirmishes and will face military trial.

Church leaders declared three days of mourning for those who died.

The sectarian unrest is being used as a means to sow discord among the population, according to Gindi.

"Egypt's people, the noble police and the great army are standing together to foil the counter-revolution," Gindi said, while the army blamed "forces of evil and darkness" for trying to "tear the national fabric" in a statement on Facebook.

It elaborated, saying that it should act as a "deterrent to all those who think of toying with the potential of this nation". The statement continued, saying that a committee would be set up to assess the damage caused by the clashes and "restore all property and places of worship to how they were".

Christian and Muslim protesters gathered in front of Cairo's High Court on Sunday afternoon as a gesture of solidarity when dozens of "neighbourhood thugs" pelted them with stones. After a brief clash between the two groups that saw rocks and stones being thrown from both sides, the protesters dispersed only to regroup outside the state television network.

Hundreds of people joined the protesters until by Sunday evening, thousands were demonstrating in Cairo's city centre, blocking traffic and were surrounded by riot police.

Both Christians and Muslims have requested increased security from the visiting interior minister Mansur Essawy, MENA news agency has said. The lack of security and police forces has brought the government under criticism, however, Essawy vowed to "improve security in the coming phase and bring back stability," MENA said.