Street clashes have killed at least 30 people in Egypt's Port Said after 21 supporters of a local football club were sentenced to death over a bloody stadium riot in the canal city.
The violence comes a day after nine were killed in protests against President Mohamed Morsi on the second anniversary of Egypt's uprising against predecessor Hosni Mubarak, in the worst crisis Morsi has faced since taking power in June.
Minutes after a Cairo court handed down the sentences on Saturday against fans of Port Said side Al-Masry over the deaths of 74 people during post-match violence last February, protesters rampaged through the city, attacking police stations and setting tyres alight.
Relatives of those condemned tried to storm the prison in Port Said where they are being held, leading to fierce clashes with security forces.
Unidentified assailants used automatic weapons against police who responded with tear gas, witnesses said.
At least 30 people died and 312 were wounded, the health ministry said, with the interior ministry saying two policemen were among those killed.
Medics told AFP all the fatalities were from gunfire.
Crowds stormed two police stations as heavy gunfire crackled through the city, where shops and businesses had closed, according to an AFP correspondent.
Ambulances ferried the injured to hospitals and mosques urged worshippers to donate blood.
The army, which earlier deployed troops to restore calm, managed to control vital public buildings, including the prison, banks and courts, witnesses said.
Clashes also erupted in the nearby canal city of Suez, where at least eight people were killed in fighting on Friday.
Protesters tried to storm the main police station, but were thwarted by police, who fired tear gas to disperse them, witnesses said.
Amid the spreading unrest, the opposition threatened to boycott upcoming parliamentary polls if Morsi does not find a "comprehensive solution" to the unrest.
The National Salvation Front, the main coalition of parties and movements opposing the ruling Islamists, called for the creation of a "national salvation" government, saying otherwise it will "not participate" in the election.
February's riots, when fans of Port Said side Al-Masry attacked players and fans of Cairo's Al-Ahly, sparked days of protests in the capital, in which another 16 people were killed.
In Cairo on Saturday, both inside and outside the court, there were explosions of joy at the verdict. Women ululated, relatives hugged each other and shouted "Allahu Akbar" (God is greatest).