CAIRO - Egypt’s military chief warned on Tuesday that the political crisis sweeping the country could lead to the collapse of the state, as thousands defied curfews and the death toll from days of rioting rose to 52.“The continuing conflict between political forces and their differences concerning the management of the country could lead to a collapse of the state and threaten future generations,” General Abdel Fattah al-Sissi, who is also defence minister, said on his Facebook page.He further warned that the political, economic, social and security problems facing Egypt constitute “a threat to the country’s security and stability,” and vowed to defend vital infrastructure, including the Suez Canal.Sissi’s warning comes as medics on Tuesday reported another three people killed in the violence sweeping Egypt, pushing to at least 52 the death toll from five days of clashes. Two people died in fighting between protesters and security forces in the riot-hit canal city of Port Said, and one was shot dead in Cairo when protesters and police clashed near Tahrir Square, the capital’s iconic hub of protest.On Sunday, President Mohamed Mursi imposed a month-long state of emergency and night-time curfews on Port Said, Ismailiya and Suez, the three provinces most affected by the rioting.But witnesses said thousands of demonstrators flooded the streets of the three Suez Canal cities Monday night in defiance of the curfews.The protesters chanted slogans against Islamist rule in Egypt, “Fall, fall the rule of the guide (of the Muslim Brotherhood), referring to Mursi, who hails from the Brotherhood.Egypt has already deployed troops to Port Said and Suez provinces, at each end of the canal that Sissi said the army would defend. “The deployment of the army in Port Said and Suez aims to protect strategic infrastructure, especially the Suez Canal, which we will not allow to be harmed,” Sissi said. But he said the army’s task was difficult.It does “not want to confront Egyptian citizens who have a right to protest” but it “has to protect vital institutions. That is why protests must be peaceful.”Meanwhile, the Egyptian judiciary has ordered the arrest of members of the “Black Bloc”, a shadowy group of militants who have appeared among protesters during the latest clashes with police, a judicial source said Tuesday.Prosecutor General Talaat Ibrahim Abdallah has authorised the arrest “of all people suspected of belonging to the group and ordered that they be brought before the courts,” the source said.The demonstrators, their faces hidden by black masks, have appeared among stone-throwing protesters during the deadly riots which have rocked Egypt since Thursday.“Inquiries have shown that the Black Bloc is an organised group which carries out terrorist actions,” said the prosecutor general’s spokesman Hassan Yassine.Presenting themselves as the defenders of protesters opposed to Mohamed Mursi’s rule against the president’s Muslim Brotherhood supporters, they reportedly model themselves on anarchist groups of the same name in Europe and the United States.Photographs showed them celebrating around a police armoured vehicle in flames in the middle of Tahrir Square this week, waving V-for-victory signs.