* Death toll in five days of violence now at 50
* Curfew imposed on Port Said, Ismailia and Suez
* President Mursi calls for dialogue
* Sceptical opposition spurns invitation (Adds protests, chants in Alexandria)
By Edmund Blair and Shaimaa Fayed
CAIRO, Jan 28 (Reuters) - A man was shot dead on Monday in a fifth day of violence that has killed 50 Egyptians and prompted the Islamist president to declare a state of emergency in an attempt to end a wave of unrest sweeping the biggest Arab nation.
Emergency rule announced by President Mohamed Mursi on Sunday covers the cities of Port Said, Ismailia and Suez. The army has already been deployed in two of those cities and ministers agreed a measure to let soldiers arrest civilians.
A cabinet source told Reuters any trials would be in civilian courts, but the step is likely to anger protesters who accuse Mursi of using high-handed tactics of the kind they fought against to oust his military predecessor Hosni Mubarak.
Egypt's politics have become deeply polarised since those heady days two years ago, when protesters were making the running in the Arab Spring revolutions that sent shockwaves through the region and Islamists and liberals lined up together.
Although Islamists have won parliamentary and presidential elections, the disparate opposition has since united against Mursi. Late last year he moved to expand his powers and pushed a constitution with a perceived Islamist bias through a referendum. The moves were punctuated by street violence.
Mursi's national dialogue meeting on Monday to help end the crisis was spurned by his main opponents.
They say Mursi hijacked the revolution, listens only to his Islamist allies and broke a promise to be a president for all Egyptians. Islamists say their rivals want to overthrow by undemocratic means Egypt's first freely elected leader.
Thousands of anti-Mursi protesters were out on the streets again in Cairo and elsewhere on Monday, the second anniversary of one of the bloodiest days in the revolution which erupted on Jan. 25, 2011 and ended Mubarak's iron rule 18 days later.
"The people want to bring down the regime," they chanted Alexandria. "Leave means go, and don't say no!" they shouted.
VOLLEYS OF TEARGAS
Propelled to the presidency in a June election by the Muslim Brotherhood, Mursi has lurched through a series of political crises and violent demonstrations, complicating his task of shoring up the economy and of preparing for a parliamentary election to cement the new democracy in a few months.
Instability in Egypt has raised concerns in Western capitals, where officials worry about the direction of a key regional player that has a peace deal with Israel.
In Cairo on Monday, police fired volleys of teargas at stone-throwing protesters near Tahrir Square, cauldron of the anti-Mubarak uprising. A car was torched on a nearby bridge.
A 46-year-old bystander was killed by a gunshot early on Monday, a security source said. It was not clear who fired.
"We want to bring down the regime and end the state that is run by the Muslim Brotherhood," said Ibrahim Eissa, a 26-year-old cook, protecting his face from teargas wafting towards him.
The political unrest has been exacerbated by street violence linked to death penalties imposed on soccer supporters convicted of involvement in stadium rioting in Port Said a year ago.
As part of emergency measures, a daily curfew will be imposed on the three canal cities from 9 p.m. (1900 GMT) to 6 a.m. (0400 GMT). Residents have said they will defy it.
The president announced the measures on television on Sunday: "The protection of the nation is the responsibility of everyone. We will confront any threat to its security with force and firmness within the remit of the law," Mursi said, angering many of his opponents when he wagged his finger at the camera.
He offered condolences to families of victims. But his invitation to Islamist allies and their opponents to hold a national dialogue was spurned by the main opposition National Salvation Front coalition. Those who accepted were mostly Mursi's supporters or sympathisers.
SENDING A MESSAGE
The Front rejected the offer as "cosmetic and not substantive" and set conditions for any future meeting that have not been met in the past, such as forming a government of national unity. They also demanded that Mursi declare himself responsible for the bloodshed.
"We will send a message to the Egyptian people and the president of the republic about what we think are the essentials for dialogue. If he agrees to them, we are ready for dialogue," opposition politician Mohamed ElBaradei told a news conference.
The opposition Front has distanced itself from the latest flare-ups but said Mursi should have acted far sooner to impose security measures that would have ended the violence.
"Of course we feel the president is missing the real problem on the ground, which is his own policies," Front spokesman Khaled Dawoud said after Mursi made his declaration.
Other activists said Mursi's measures to try to impose control on the turbulent streets could backfire.
"Martial law, state of emergency and army arrests of civilians are not a solution to the crisis," said Ahmed Maher of the April 6 movement that helped galvanise the 2011 uprising. "All this will do is further provoke the youth. The solution has to be a political one that addresses the roots of the problem."
Rights activists said Mursi's declaration was a backward step for Egypt, which was under emergency law for Mubarak's entire 30-year rule. His police used the sweeping arrest provisions to muzzle dissent and round up opponents, including members of the Brotherhood and even Mursi himself.
Heba Morayef of Human Rights Watch in Cairo said the police, still hated by many Egyptians for their heavy-handed tactics under Mubarak, would once again have the right to arrest people "purely because they look suspicious", undermining efforts to create a more efficient and respected police force.
"It is a classic knee-jerk reaction to think the emergency law will help bring security," she said. "It gives so much discretion to the Ministry of Interior that it ends up causing more abuse, which in turn causes more anger." (Additional reporting by Yasmine Saleh in Cairo, Yusri Mohamed in Ismailia and Abdelrahman Youssef in Alexandria; Editing by Giles Elgood, Peter Millership and Alastair Macdonald)