British authorities have now arrested more than 1,000 people following days of rioting involving violence, arson and looting as well as racist attacks targeting Muslims and migrants, a national policing body said on Tuesday.

The riots, which followed the killings of three young girls in the northern English town of Southport, began after the July 29 attack was wrongly blamed on an Islamist migrant based on online misinformation.

Violence broke out in cities across England and also in Northern Ireland, but there have been fewer instances of unrest since last week after efforts to identify those involved were ramped up.

Many have been swiftly jailed, with some receiving long sentences.

The National Police Chiefs' Council said in its latest update that 1,024 had been arrested and 575 charged across the UK.

Those arrested include a 69-year-old accused of vandalism in Liverpool and a 11-year-old boy in Belfast.

A 13-year-old girl pleaded guilty to violent disorder at Basingstoke Magistrates' Court, prosecutors said, having been seen on July 31 punching and kicking the entrance to a hotel for asylum seekers.

"This alarming incident will have caused genuine fear amongst people who were being targeted by these thugs – and it is particularly distressing to learn that such a young girl participated in this violent disorder," prosecutor Thomas Power said.

The last time Britain witnessed widespread rioting was in 2011, when the fatal shooting of a Black man by police triggered several days of street violence.

Fast and tough judicial action was viewed as helping quell the unrest in 2011, when around 4,000 people were arrested over several weeks.