Egypt’s President Mohammed Morsi is hoping that by adopting a hard line, he can restore calm after four days of violence that have presented another tough challenge to his leadership.After being criticised for his relative silence, he appeared on state television to give a firm address on Sunday night.A state of emergency and curfews were declared in three cities along the strategically important Suez Canal: Suez, Ismailia and Port Said."If I must, I will do much more for the sake of Egypt. This is my duty and I will not hesitate,” Mr Morsi said.On Saturday, riots broke out in Port Said after 21 supporters of the local football club, al-Masry, were sentenced to death for their role in the country’s worst ever football violence.Seventy-four people were killed - mostly visiting fans - at a home match against Cairo’s al-Ahly team almost a year ago.In court, relatives of those convicted lashed out at police officers and then headed to the prison where the men were held. Large crowds joined in attacks on police stations and government buildings.As police retreated from the streets, soldiers moved in with tanks and armoured vehicles. Live ammunition and tear gas were used against the protesters.Dark moodAnger is still simmering in Port Said where more than 30 people have been killed in the latest unrest."Snipers were on top of buildings near and around the prison, also on the prison. People were shot in the head,” one resident, Amr Mubarak, told the BBC.He explained how his 17-year-old brother, Mohammed, was arrested after attending last year’s football match and still faces trial but maintains he did nothing wrong."We will not allow our children to be scapegoats for [President] Morsi,” Amr said. "Morsi is the same as [ousted President Hosni] Mubarak. The Mubarak regime did not change until this day. Morsi doesn’t deserve to be the president of Egypt.”Many locals in Port Said express a total lack of faith in the security services and suggest the court verdicts were politically motivated."The motive behind the sentencing was political - to please one side on account of the other. [President] Morsi committed a grave mistake. This is unjust,” says a businessman, Tawfik al-Esawy.Some have claimed that the president intervened to avoid another confrontation with the die-hard fans of al-Ahly, known as Ultras."Morsi is behind the sentencing because he didn’t want to anger the Ultras. He wanted to absorb their anger because he feared what they would do,” says Ali, an al-Masry supporter who was at last February’s ill-fated match.Witnesses said the city remained on edge overnight with the military still guarding key installations, including the canal.Calmer in CairoCairo has seen its own share of clashes in recent days with events to mark the second anniversary of the start of the 25 January uprising that unseated the former president. At least a dozen people were killed in protests against Mr Morsi.Yet there was a sense of relief and vindication among al-Ahly fans concerning Saturday’s verdicts."I went to the club to celebrate and join the relatives of those killed,” says Ahmed, who lost friends in last year’s attack. "There is no reason for people in Port Said to get angry. It says in the Koran that whoever kills should be killed. They committed murder.”"I was happy. This was the first trial since the revolution where we felt like just sentences had been given,” says Salah al-Sheikh.The verdicts of another 52 defendants facing charges in the case are due on 9 March. They include security officials.But many al-Ahly supporters feel this should not be the end of the matter."We believe that only 80% of those involved have been caught. We think there are 20% still free and they are from the old regime. They’re powerful people and that’s why they’re not in jail,” adds Salah.Suspicions lingerEgyptians watched in horror on 1 February 2012 as live cover of the football match that al-Masry won 3-1, turned to mass bloodshed. Home fans invaded the pitch and then turned on their rivals. Dozens were beaten or crushed to death.Rumours persist that Mubarak loyalists or the generals, who ruled Egypt at the time, organised the fighting to punish the Ultras of al-Ahly.The Ultras took a front-line role in protests in Cairo’s Tahrir Square two years ago.They continued to clash with security forces in subsequent protests over the military’s handling of the period of democratic transition.Last year, an Egyptian parliamentary inquiry into the deaths at Port Said found that fans and lax security were responsible."Security facilitated, allowed and enabled this massacre,” said the head of the investigation, Ahmed Thabet.Routine checks were not carried out to establish that fans had no weapons and riot police stood by during the scenes of chaos in the stadium. Steel exit doors were bolted shut.Appeal for dialogueSince President Morsi took office last June, his critics complain that he has failed to hold former officials accountable for their alleged crimes and carry out much-needed reforms, particularly to the interior ministry. He has failed to fill a security vacuum, making his task of dealing with a growing economic crisis much harder.Although small clashes took place in Ismailia and Suez on Sunday, there is no doubt that Mr Morsi decided to prioritise safety along the Suez Canal with his latest measures.The waterway is a vital shipping route and remains one of Egypt’s main sources of foreign revenue.In Cairo, the president will also be feeling diplomatic pressure to show he is taking decisive action to restore order. A return to roadblocks near Tahrir Square closed both the United States and British embassies to the public on Sunday.With the need for national unity painfully apparent, Mr Morsi also reached out to the opposition in his address saying: "There is no alternative to dialogue.”He invited leading figures, including the former foreign minister and head of the Arab League, Amr Moussa, and leftist Hamdeen Sabahi, to join other political forces for talks on Monday.In such tough times, he must be calculating that he sorely needs some new friends.