Chief Constable Hugh Orde, commander of Northern Ireland's mostly Protestant police, blamed the Protestant marching brotherhood for inspiring the riots, which were the worst committed by the Protestant side of the community in a decade.
At midday Sunday, police still had no firm tally of the damage, but estimated that several dozen of police officers, soldiers and civilians had been wounded in mob violence that ran into Sunday morning.
Heavily armored police backed by British troops came under attack in several parts of Belfast and a half-dozen other predominantly Protestant towns and villages.
In the most intense exchanges, masked Protestant men and youths hurled homemade grenades and gasoline bombs and fired automatic gunfire at security force positions in northwest Belfast, about a half-mile from the spot where Orangemen had been prevented Saturday from marching past a hostile Catholic section of Springfield Road.
In several locations, Catholic hard-liners also joined in the all-night fray, tossing rocks, bottles and other objects into police lines and the Protestant crowds beyond.
The Protestant riots were the most widespread in Belfast since July 1996, when Protestants rioted across Northern Ireland for four nights straight over another blocked Orange Order parade.
The police chief said he feared that Belfast could suffer a second night of rioting Sunday, and appealed to Orange leaders to cancel any future protests they are planning.
"The Orange Order must bear substantial responsibility for this. They publicly called people on to the streets. I think if you do that, you cannot then abdicate responsibility," Orde said.
But in a statement, the Orange Order, Northern Ireland's largest fraternal group with more than 50,000 members, rejected Orde's criticisms as "intemperate, inflammatory and inaccurate." The group described the security forces' operations against the Orange Order road blockades and the rioters "policing at its worst."
Some moderate Protestant politicians also criticized police for using excessive force and failing to distinguishing between friend and foe.
"While I'm always sympathetic to police, I am shocked at some of tactics being used," said Reg Empey, leader of the Ulster Unionist Party. "I have personally witnessed women, who had been trying to prevent stoning, being pushed to the ground for no justifiable reason."
Catholics, about 40 percent of Northern Ireland's 1.7 million population, weighed whether to attend Sunday services at their local church, particularly those that lie near working-class Protestant districts.
At one frequently attacked church in Ballymena, northwest of Belfast, the parish priest opted to cancel Mass and refer worshippers to a different church in a more middle-class area, where rioting did not occur.
"It's better to be safe than sorry," said the Rev. Paul Symonds of the Harryville church in south Ballymena, where Protestant mobs angered by other restrictions on Orange Order parades frequently intimidated Mass-goers in the late 1990s.
Each summer, Northern Ireland endures inflamed communal tensions because of mass demonstrations by the Orange Order, a legal organization that was instrumental in founding Northern Ireland as a predominantly Protestant state 85 years ago.
Over the past decade, Catholic hard-liners led by Sinn Fein, the Irish Republican Army-linked party, have violently opposed Orange parades that pass near Catholic areas. Britain in 1997 formed a Parades Commission that has imposed restrictions on most of the disputed parades.