The sentence of the Southport killer will not be referred to the court of appeal under the unduly lenient sentence scheme, the attorney general has said.

Axel Rudakubana, 18, was handed a 52-year minimum sentence for murdering three girls at a dance class, the second-longest sentence imposed by the courts in English history, but the Southport MP Patrick Hurley previously asked the attorney general to review the sentence as “unduly lenient”, saying it is “not severe enough”.

The sentence also prompted criticism from the parent of a victim who survived the attack, who told the Sun that Rudakubana’s crimes were so horrific that he should “rot in jail” and the “law needs changing”.

Rudakubana cannot legally receive a whole-life order, a punishment reserved for offenders aged 21 and over or, in rare cases, those aged 18 to 20, because he was 17 at the time of the attack last year.

He killed nine-year-old Alice da Silva Aguiar, six-year-old Bebe King and seven-year-old Elsie Dot Stancombe in a Taylor Swift-themed dance class in Southport in July 2024. He also attempted to murder eight other children, who cannot be named for legal reasons, the class instructor Leanne Lucas and the businessman John Hayes.

In statement, the attorney general, Lord Hermer KC, said it was understandable that he had been asked to review the sentence under the unduly lenience sentence scheme, which is designed to identify and remedy gross errors made by judges.

He described the murder of the three young girls as “senseless and barbaric”, adding: “No words come anywhere close to expressing the brutality and horror in this case.”

But he said that after “careful consideration” of independent legal advice and consultation with leading criminal barristers and the Crown Prosecution Service, he has concluded that this case “cannot properly be referred to the court of appeal”.

“No one would want the families to be put through an unnecessary further court process where there is no realistic legal basis for an increased sentence.”

After the sentencing, the Conservative leader, Kemi Badenoch, backed by the shadow home secretary, Chris Philp, said there was a “strong case” for amending the law to allow for whole-life orders to be imposed on people aged under 18 in some cases. She said this was something which the Tories “will start to explore”.

The prime minister, Keir Starmer, has said that the “vile offender will likely never be released”.

Three separate referrals were made to the government’s anti-terror programme, Prevent, about Rudakubana’s behaviour in the years before the attack, as well as six separate calls to police.

Earlier this month, it emerged that the misspelt name of Rudakubana in the government’s database for potential terrorists may have hampered his assessment as a possible mass murderer.

His surname was correctly recorded in 2019, but misspelled in 2021, which meant that anti-terror officers “may not have been able to see a previous referral”, a rapid learning review of the Prevent programme disclosed.