LONDON — Declaring "we will not allow a culture of fear to exist on our streets," Prime Minister David Cameron said Thursday that police across Britain had so far made more than 1,200 arrests over the country's worst civil unrest in memory.
Police levels London would remain elevated at 16,000 through the weekend, Cameron told an emergency session of parliament.
He promised tough measures to stop further violence and said "nothing should be off the table," including water cannons and plastic bullets.
"The whole country has been shocked (by the riots). ... It is criminality, pure and simple, and there is absolutely no excuse for it," Cameron told lawmakers in the House of Commons.
He said riot-hit businesses would receive help to get back on their feet, and promised to look to the United States for help in fighting the street gangs he blamed for helping spark Britain's riots.
Cameron told lawmakers that he would look to cities like Boston for inspiration. He also mentioned former Los Angeles and New York Police Chief Bill Bratton as a person who could help offer advice.
The government, police and intelligence services were looking at whether there should be limits on the use social media sites like Twitter and Facebook to spread disorder, he said.
Meanwhile the number of people arrested in London alone rose to 922 since trouble began on Saturday, with 401 suspects charged.
Deputy Assistant Commissioner Stephen Kavanagh said raids to round up suspects began overnight, and more than 100 warrants would be executed.
Hugh Orde, head of the Association of Chief Police Officers, said there would be "hundreds more people in custody" by the end of the day.
The Guardian newspaper reported that an 11-year-old girl had been charged with criminal damage and jailed pending a court hearing, citing Nottinghamshire police.
The paper also said three people have been charged with posting messages on Facebook encouraging disorder, one in Sussex in the south and two in Lancashire in the north-west.
However, British cities were largely quiet by Thursday morning.Grace of a grieving father speaks to a wounded Britain
Meanwhile, Saturday's English Premier League soccer game between Tottenham and Everton — originally scheduled for Tottenham's north London stadium — had been postponed due to the riots. The unrest flared initially in Tottenham.
Deputy Prime Minister Nick Clegg said the "sociological debate" about the origins of the violence was for the future.
"Right now, it's important that people are reassured that their streets are made safe, their homes are made safe and society is allowed to move on," Clegg told BBC radio.Riots reveal London’s two disparate worlds
Libyan state television, meanwhile, added its analysis of the situation, claiming Cameron was using "Irish and Scottish mercenaries" to tame riots in England.
"The rebels of Britain approach Liverpool in hit-and-run battles with Cameron's brigades and mercenaries from Ireland and Scotland. God is Greatest," said a breaking news caption on Libyan TV's morning program, according to Reuters.
"These (riots in Britain) are not protests fomented by foreign intelligence services," said the show host, contrasting the turmoil in Britain with what Tripoli calls a foreign-hatched plot to unseat Libya's lawful government.Story: Deaths of 3 Muslims stoke ethnic tensions in UK
There was a brief outbreak of trouble in Eltham, southeast London, where a group of largely white and middle-aged men who claimed to be defending their neighborhood pelted police with rocks and bottles.
Police said the incident had been "dealt with" and a group was dispersed.
There were chaotic scenes at courthouses, several of which sat through the night to process scores of alleged looters and vandals.Far-right group calls for safe and sober vigilantism
Other cities where looters had rampaged earlier this week also came through the night largely unscathed, though for the first time minor disturbances were reported in Wales.
Also on Wednesday, tensions flared in Birmingham, where a murder probe was opened after three men were killed in a hit-and-run incident as they took to the streets to defend shops from looting.
Chris Sims, chief constable of West Midlands Police, said a man had been arrested on suspicion of murder.Are London looters unloading on Craigslist?
The violence has revived debate about the Conservative-led government's austerity measures, which will slash 80 billion pounds ($130 billion) from public spending by 2015 to reduce the country's swollen budget deficit.
Cameron's government has slashed police budgets as part of the cuts. A report last month said the cuts will mean 16,000 fewer police officers by 2015.
London Mayor Boris Johnson — like Cameron, a Conservative — broke with the government to say such cuts are wrong.
"That case was always pretty frail and it has been substantially weakened," he told BBC radio. "This is not a time to think about making substantial cuts in police numbers."
The Associated Press and Reuters contributed to this report.