* Three people shot dead, hundreds injured in new clashes
* Deadly Port Said riots erupted after court verdict
* Protests flared during revolution anniversary
* Opponents say President Mursi betrayed revolution (Adds Mursi to address nation)
By Edmund Blair and Shaimaa Fayed
CAIRO, Jan 27 (Reuters) - Three people were shot dead and hundreds were injured in Egypt's Port Said on Sunday during the funerals of 33 protesters killed at the weekend, part of a wave of violence piling pressure on Islamist President Mohamed Mursi.
State television said Mursi would address the nation later on Sunday. Forty-five people have been killed in demonstrations around the country since Thursday and his opponents have called for more protests on Monday.
Port Said's head of hospitals, Abdel Rahman Farag, told Reuters an 18-year-old man and two other people died from gunshot wounds on Sunday. More than 416 people suffered from teargas inhalation, while 17 were wounded by gunshots, he said.
As coffins were carried through the streets earlier, some in the crowd chanted for revenge or shouted anti-Mursi slogans. "Our soul and blood, we sacrifice to Port Said," they said.
Gunshots had killed many of the 33 who died on Saturday when residents went on the rampage after a court sentenced 21 people, mostly from the Mediterranean port, to death for their role in deadly soccer violence at a stadium there last year.
A military source said many people in Port Said, which lies next to the increasingly lawless Sinai Peninsula, possess guns. But it was not clear who was behind the deaths and injuries.
In Cairo, police fired teargas at dozens of stone-throwing protesters in a fourth day of clashes over what demonstrators there and in other cities say is a power grab by Islamists two years after Hosni Mubarak was overthrown.
The protesters accuse Mursi, elected in June with the support of his Muslim Brotherhood group, of betraying the democratic goals of the revolution. Most of the deaths since Thursday were in Port Said and Suez, both cities where the army has now been deployed.
The violence adds to the daunting task facing Mursi as he tries to fix a beleaguered economy and cool tempers before a parliamentary election expected in the next few months which is supposed to cement Egypt's transition to democracy.
It has exposed a deep rift in the nation. Liberals and other opponents accuse Mursi of failing to deliver on economic promises and say he has not lived up to pledges to represent all Egyptians. His backers say the opposition is seeking to topple Egypt's first freely elected leader by undemocratic means.
Although Sunday's violence was less severe than the previous two days, Mursi may have little respite. The opposition Popular Current and other groups have called for more protests on Monday to mark what was one of the bloodiest days of the 2011 uprising.
The Popular Current, led by leftist Hamdeen Sabahy, said it "denounces the state of silence of the presidency and the government during the sad events that the country went through the past 48 hours".
"BLOOD BEING SPILT"
On a bridge close to Tahrir Square, youths hurled stones at police in riot gear who fired teargas to push them back towards the square, the cauldron of the uprising that erupted on Jan. 25, 2011 and toppled Mubarak 18 days later.
"None of the revolution's goals have been realised," said Mohamed Sami, a protester in Cairo's Tahrir Square on Sunday.
"Prices are going up. The blood of Egyptians is being spilt in the streets because of neglect and corruption and because the Muslim Brotherhood is ruling Egypt for their own interests."
Clashes also erupted in other streets near the square. The U.S. and British embassies, both close to Tahrir, said they were closed for public business on Sunday, normally a working day.
The army, Egypt's interim ruler until Mursi's election, was sent back onto the streets to restore order in Port Said and Suez, which both lie on the Suez canal. In Suez, at least eight people were killed in clashes with police.
Egypt's defence minister who also heads the army, Abdel Fattah al-Sissi, called for the nation to stand together and said the military would not prevent peaceful protests. But he called on demonstrators to protect public property.
Many ordinary Egyptians are frustrated by the regular escalations that have hurt the economy and their livelihoods.
"They are not revolutionaries protesting," said taxi driver Kamal Hassan, 30, referring to those gathered in Tahrir. "They are thugs destroying the country."
CALL FOR DIALOGUE
The National Defence Council, headed by Mursi, called on Saturday for national dialogue to discuss political differences.
That offer has been cautiously welcomed by the opposition National Salvation Front. But the coalition has demanded a clear agenda and guarantees that any agreements will be implemented.
The Front, formed late last year when Mursi provoked protests and violence by expanding his powers and driving through an Islamist-tinged constitution, has threatened to boycott the parliamentary poll and call for more protests if its demands are not met, including for an early presidential vote.
Egypt's transition has been blighted from the outset by political rows and turbulence on the streets that have driven investors out and kept many tourists away. Its currency, the pound, has steadily weakened against the dollar.
The Port Said clashes erupted after a judge sentenced 21 men to death for involvement in 74 deaths at a soccer match on Feb. 1, 2012 between Cairo's Al Ahly club and the local al-Masri team. Many of the victims were fans of the visiting team.
There were 73 defendants in the case. Those not sentenced on Saturday will face a verdict on March 9, the judge said.
Al Ahly fans cheered the verdict after threatening action if the death penalty was not meted out. But Port Said residents were furious that people from their city were held responsible.
(Additional reporting by Yusri Mohamed in Ismailia and Yasmine Saleh in Cairo; editing by Philippa Fletcher)