Two 12-year-old boys have become the youngest to be convicted following recent disorder in the UK.

One boy, who cannot be named for legal reasons, was caught on CCTV throwing an object at police during unrest in Southport. He admitted violent disorder at Liverpool Youth Court.

The other 12-year-old threw a missile at a police van in Manchester. He admitted two charges of violent disorder at the city’s magistrates’ court.

The two boys were among several people convicted on Monday following disorder that began after three young girls were killed in a knife attack in Southport.

In Liverpool, one of the 12-year-olds was caught on CCTV throwing the item at police and then riding off on a bicycle during a disturbance on 30 July.

The city’s youth court was told the boy was the youngest person to appear before the courts in relation to unrest in Southport.

He was released on bail ahead of sentencing on 17 September.

The other 12-year-old was part of a group on 31July that gathered outside a Holiday Inn hotel housing asylum seekers, Manchester Magistrates’ Court heard.

The prosecution said the boy, who also cannot be named for legal reasons, was seen in footage handing a rock to another youth during the disorder and was part of a group attack on a bus.

He was subsequently seen on 3 August filmed by police kicking the front window of a vape shop and throwing a missile at a police van, the prosecution told the court.

District judge Joanne Hirst said the case was “very serious”, adding it was the first she had dealt with of a person “attending both incidents” of disorder.

The boy was remanded to local authority accommodation and will be sentenced at Manchester Magistrates’ Court on 2 September.

At Plymouth Crown Court, a man who grabbed a police officer’s baton and ran off with it was jailed for three years.

Guy Sullivan, 43, of New George Street, Plymouth, admitted a charge of violent disorder relating to the violence in the city on 5 August.

The court heard a lone officer had been using his baton to push back protesters around him, when Sullivan came behind the officer and grabbed the baton out of his hands.

The officer was then pulled to the ground and attacked by other protesters as onlookers filmed and shouted “get him”, “do him” and “let him have it”.

Sentencing, judge Robert Linford said: “He [Pc Hannaford] must have been terrified, not withstanding his years of experience. He says so close to his retirement this incident has left a sour taste.

“You played your part in that mob violence. The courts are going to come down hard on people who are part of that widespread disorder.”

In court, a letter from Sullivan was read out saying he was “sorry from the bottom of my heart” and he would miss his son’s first Christmas.

At Teeside Crown Court, a 22-year-old man was jailed for 26 months after throwing a vacuum cleaner through the window of student house.

Thomas Roger, who was also seen throwing bricks at police, admitted violent disorder and possession of an offensive weapon during a 1,000-strong protest in Middlesbrough on 4 August.

The court heard the landlord of the property said: “I feel angry and disappointed with the thugs, especially the idiot with the Hoover.”

Meanwhile in Southampton, a scaffolder was jailed for 12 months after taking a knuckle-duster to an anti-immigration protest.

Lee James, 42, of Southampton, admitted to possessing the weapon during a demonstration in the city.

Prosecutor Richard Onslow said James had taken the knuckle-duster out of his van to the protest “on a whim” and told police it was for his protection.

Southampton Crown Court heard James was later recorded in a video interview at the protest being “very blasé about waving it around his hands as he spoke”.

Sentencing James, judge Christopher Parker KC said: “You chose to go along to take part in the protest, but you also chose to take with you a knuckle-duster whose only purpose can be to cause injury to other human beings.”

Speaking on Monday during a visit to Hull to see police to discuss the violent disorder, Transport Secretary Louise Haigh said: “We welcome that there has been a de-escalation this weekend.

“But we’re certainly not complacent and remain on high alert.

“We also recognise that the job is not done until people feel safe in their communities, but thanks to the work of our police officers, prosecutors … and judiciary, we have seen a swift response from the justice system.”

Number 10 said the government was “not complacent” as “the work is not done” in dealing with the fallout from violence.

Prime Minister Sir Keir Starmer has cancelled a holiday to Europe to “ensure that we can respond to the disorder”, a spokeswoman said.

Far-right rallies and violence broke out in parts of the UK after the killing of three young girls in Southport. False claims had spread online the suspect was an asylum seeker who arrived in Britain by boat.

So far, 927 people have been arrested and 466 charged in relation to the recent disorder, a spokesperson for the National Police Chiefs’ Council (NPCC) said on Monday.