Facing a public backlash against police restraint during four nights of rioting, Prime Minister David Cameron offered his toughest line yet on the violence, saying Wednesday that officers were authorized to use rubber bullets and water cannons in what he described as a “fightback” to retake English streets.

His comments came as Britain, a nation of laws and a leading critic of crackdowns by totalitarian governments overseas, engaged in a heated debate over the methods it should use to combat lawlessness at home. As reinforcements were rushed to bolster police forces overwhelmed on Tuesday in Manchester and Birmingham, officials also warned that frustrated citizens were grouping together and sliding into vigilantism.

As of late Wednesday, however, much of the country appeared calm, with stores reopening in some hard-hit neighborhoods, albeit with a large police presence on the streets. But many people still spoke of a sense of fear after the most deadly night of the riots yet, with authorities in Birmingham calling for calm amid worries about rising racial tensions after a fatal incident.

Late Tuesday, a car carrying alleged looters ran over and killed three South Asian men who were out protecting their neighborhood. Birmingham police arrested a suspect; though they did not disclose his race, missives circulating on Twitter said the driver was black, ratcheting up local tensions.

Among the dead was a 21-year-old whose father, Tariq Jahan, gave him CPR on the scene only to watch him die. In an emotional appeal, Jahan begged for an end to the violence, saying the tragedy should become a turning point for peace and not a rallying cry for “revenge.”

“I can’t describe what it is like to lose your son,” he said. “I don’t know what is happening to England and why innocent people have to die.”

He later added, “Blacks, Asian, whites, we all live in the same community, why do we have to kill one another?” He asked that everyone honor his son by “not going out tonight.”

Addressing public anger

Almost since the riots began after the fatal police shooting of a black resident of north London last week, critics have called for a tougher response to the rash of disturbances that has sullied Britain’s image less than a year before London is set to host the 2012 Olympic Games.

Underscoring the public anger, a YouGov poll for the Sun newspaper published Wednesday showed 90 percent of those surveyed calling for the use of water cannons against rioters, 77 percent supporting the deployment of the army and 33 percent saying police should be permitted to fire live ammunition.

A majority — 57 percent — said Cameron had been managing the crisis poorly, an impression he apparently sought to dispel Wednesday. “There are pockets of our society that are not just broken but frankly sick,” Cameron said, pledging that “nothing is off the table” to halt the violence and catch looters. He said he would move to publish images of of rioters captured by surveillance cameras, without “any phony concerns about human rights getting in the way.”

The root cause of the riots, Cameron said, “is a compete lack of responsibility in parts of our society. People are allowed to feel that the world owes them something, that their rights outweigh their responsibilities and that their actions do not have consequences. Well, they do have consequences.”

On Wednesday, police appeared to be launching a more aggressive effort to track down looters, with footage showing Manchester police rounding up suspects after a gang of youths set fire to a retail store, vandalized businesses and engaged in running battles with officers Tuesday night. Yet those images, circulating on the Internet, were taken by some as evidence that Manchester police had begun using heavy-handed tactics.

With more than 1,200 people arrested nationwide and London jails filled to capacity, the courts were working into the night to process detainees.

Some of those arrested are as young as 11. But others have turned out not to be lost youths, as they have been portrayed over the course of the riots. British tabloids were quick to name and shame a 31-year-old elementary school tutor with a $1,600 monthly salary who was caught looting an electronics shop.

Cameron said harsher tactics — although authorized — would be deployed only if necessary. But police officials also suggested that the kind of methods the prime minister discussed may be inappropriate.

Sir Hugh Orde, head of Britain’s Association of Chief Police Officers, sought to defend law enforcement tactics used thus far and to tone down the tough talk coming from political leaders. He warned that water cannons, in particular, would be useless in the kind of fast-moving cat-and-mouse games that rioters have been playing with police and that rubber bullets should be deployed only in situations in which officers are coming under live fire.

He appeared to remind the nation that social disturbances are handled differently in democracies.

“We’ll do it in the British style,” Orde told the BBC. “With a minimal use of force.”

Fears of vigilantism

Though many concede that the police were simply overwhelmed by the scale of the violence in the first 48 hours of the rioting, some critics have continued to call the law enforcement response “timid.” In October, a police officer is set to stand trial for pushing a man during a protest in London in 2009, leading to his death. Some have said that the charges against that officer have discouraged more aggressive police tactics in the past four days.

Regardless, some frustrated residents have opted to protect the streets themselves, leading authorities to warn against a wave of vigilantes. On Monday night in the Stoke Newington neighborhood of London, for instance, a group of Turkish waiters and shop owners banded together to chase off a gang of rioters. A Sikh temple in west London has rallied hundreds of faithful to protect the streets in its community, including burly members of the congregation toting cricket bats.

In the Enfield neighborhood of north London, where looters set ablaze a Sony distribution center, robbing dozens of workers of jobs, hundreds of furious residents have organized to help police patrol the neighborhood.

Bob Barnard, owner of an Enfield jewelry store for 30 years who lost $8,000 worth of merchandise in looting Monday night, said, “I think everybody feels the police have backed off.” He added, “We’ve had 1,500 people on the streets declaring they would protect their own area. . . . Had the police done the job the way they should have, they would not have to do it.”

Special correspondent Rebecca Omonira-Oyekanmi contributed to this report.