The Prime Minister, Sir Keir Starmer, has said swift justice including sentencing has been a deterrent to more violent disorder.

There do not appear to have been any new anti-immigration protests in England overnight. Unrest erupted last week after misinformation was spread online about the attacker who stabbed three girls to death in Southport.

Sir Keir told an emergency Cobra meeting on Thursday that police needed to remain on “high alert”.

More than 500 people have been arrested, with more than a dozen convicted of offenses and sentenced. A quarter of those charged are under the age of 21.

Riots broke out across England last week, from Plymouth on the south coast to Sunderland in the North East.

There were also riots in Belfast, Northern Ireland.

Crowds were seen attacking mosques; accommodation housing asylum seekers, cars and buildings including a library were set on fire; and shops were looted.

Many police officers were injured, with more than 50 suffering broken bones, concussion, bruising and head wounds during a single incident at the Rotherham hotel riot.

So far, 149 charges have been brought with police expecting the number to “rise significantly” as suspects are fast-tracked to appear in court.

Tough sentences will continue with maximum publicity to try to deter future violence, the BBC understands.

Almost 6,000 extra public order officers mobilised earlier in the week remain in place.

The Mayor of London, Sadiq Khan, urged the government to revisit new social media rules, saying the recent disorder showed regulations due to come into force were “not fit for purpose”.

The Online Safety Act will, for the first time, make firms legally responsible for keeping users safe when they use their services.

It will require platforms to put in place clear and proportionate safety measures to prevent illegal and other harmful content from appearing and spreading on their sites.

Platforms will be required to take “robust action” against illegal content and activity, including around offences such as inciting violence.

The biggest platforms could face billions of pounds in fines if they do not comply.

After the stabbings in Southport, an incorrect name and a false story around the background of the suspected perpetrator spread online.

Mr Khan said this misinformation spread on social media showed reform of the regulation was needed.

“The way the algorithms work, the way that misinformation can spread very quickly and disinformation … that’s a cause to be concerned, we’ve seen a direct consequence of this,” he told the Guardian.

In recent days Elon Musk, the owner of X, has been heavily criticised for posts about the disorder in the wake of the Southport stabbings.

The billionaire was called “deeply irresponsible” by Justice Secretary Heidi Alexander for posting that “civil war is inevitable” in the UK.

He also reposted an image of a fake news headline about the UK’s response to riots.

Gavin Stephens, chairman of the National Police Chiefs’ Council, has warned that those “intent on violence and destruction have not gone away”.

“We’ve seen on the footage that we get back from the scene, young people, children, are on the fringes of it, and in that mob mentality can get drawn in,” he said on Thursday.

“I think the youngest arrest was 11 years old. So, I think to have conversations with young people, children, teenagers over the course of the next few days is really, really important.”