CAIRO/ISMAILIA, Egypt: Egyptian protesters defied an overnight curfew in restive towns along the Suez Canal, attacking police stations after Islamist President Mohammad Mursi imposed emergency rule to end days of clashes that have left at least 52 people dead.

At least two men died in overnight fighting in the canal city of Port Said, the latest unrest in a wave of violence unleashed last week on the eve of the anniversary of the 2011 revolt that brought down autocrat Hosni Mubarak.

Political opponents spurned a call by Mursi for talks on Monday to try to end the violence. Instead, huge crowds of protesters took to the streets in Cairo and Alexandria, and in the three Suez Canal cities - Port Said, Ismailia and Suez - where Mursi imposed emergency rule and a curfew on Sunday.

"Down, down with Mohammad Mursi! Down, down with the state of emergency!" crowds shouted in Ismailia. In Cairo, flames lit up the night sky as protesters set vehicles ablaze.

The demonstrators accuse Mubarak's successor Mursi of betraying the two-year-old revolution. Mursi and his supporters accuse the protesters of seeking to overthrow Egypt's first ever democratically elected leader by undemocratic means.

Debris from days of unrest was strewn on the streets around Cairo's Tahrir Square, cauldron of the anti-Mubarak uprising.

Youths clambered over a burned-out police van. But unlike on previous mornings in the past few days, there was no early sign of renewed clashes with police.

In Port Said, men attacked police stations after dark. A security source said some police and troops were injured. A medical source said two men were killed and 12 injured in the clashes, including 10 with gunshot wounds.

"The people want to bring down the regime," crowds chanted in Alexandria. "Leave means go, and don't say no!"

Since Mubarak was toppled, Islamists have won two referendums, two parliamentary elections and a presidential vote.

But that legitimacy has been challenged by an opposition that accuses Mursi of imposing a new form of authoritarianism, and punctuated by repeated waves of unrest that have prevented a return to stability in the most populous Arab state.

The army has already been deployed in Port Said and Suez and the government agreed a measure to let soldiers arrest civilians as part of the state of emergency.

WESTERN CONCERNS

The instability has provoked unease in Western capitals, where officials worry about the direction of a powerful regional player that has a peace deal with Israel. The United States condemned the bloodshed and called on Egyptian leaders to make clear violence is not acceptable..

In Cairo on Monday, police fired volleys of teargas at stone-throwing protesters near Tahrir. Demonstrators burned two police vehicles and stormed into the downtown Semiramis Intercontinental hotel.

The political unrest in the Suez Canal cities 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.

Mursi's invitation to opponents to hold a national dialogue with the Islamists on Monday was spurned by the main opposition National Salvation Front coalition, which rejected it as "cosmetic".

The only liberal politician who attended, Ayman Nour, told Egypt's al-Hayat channel after the meeting ended late on Monday that attendees agreed to meet again in a week.

He said Mursi had promised to look at changes to the constitution requested by the opposition but did not consider the opposition's request for a government of national unity.

The president announced the emergency 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.

His demeanour infuriated his opponents, not least when he wagged a finger at the camera.

Some 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."