Andy Burnham has said he “wouldn’t forgive myself” if he did not try to lessen the “anguish” of Pc Andrew Harper’s family, as the Prime Minister seeks to prevent the early release of the police officer’s killers.

Mr Burnham has ordered Justice Secretary Alex Norris to draw up plans to free up prison space for serious offenders, and said he is “increasingly confident” Pc Harper’s killers will not be released early from their sentences as a result.

Speaking to LBC, the Prime Minister was asked if he had a message for Aimee Harper, the sister of the police officer who died in the line of duty in 2019, and who had shared with the broadcaster her experience of sitting in the courtroom with his killers.

Asked what he would directly say to Ms Harper, Mr Burnham replied: “That I hear you, I feel for you. I wouldn’t forgive myself if I didn’t do everything I possibly could to try and lessen your anguish, and I am doing that.

“I am turning over every stone. I am looking at everything. I am pushing the system to go further.”

He added: “That’s the way I go about my job. I listen to people. I continually push myself and the system to do more. In this instance, I think there is more that can be done.”

Mr Burnham pointed to returning foreign national offenders, dealing with the issue of those serving Imprisonment for Public Protection (IPP) sentences, an indeterminate jail term, as means of freeing up prison space.

The Prime Minister said: “I’m not making comments today in a knee-jerk way because I wouldn’t raise false hope of people.

“I’m doing it in a considered way, having looked in detail at the situation, having considered a range of advice. I am confident that we can develop a plan to free up more spaces in the prison estate, so that we can ensure more serious offenders serve their full term.”

Mr Burnham has come under pressure from 50 policing leaders from across the UK to use “every lawful option” to prevent the early release of Pc Harper’s killers.

A letter from chief constables and other law enforcement leaders also called on the Prime Minister to “establish an additional public protection safeguard” for the most serious offenders, when future early release schemes are floated.

The leaders, who included Met Commissioner Sir Mark Rowley, Greater Manchester Chief Constable Stephen Watson and National Crime Agency director general Graeme Biggar, also said families and victims “must be properly considered whenever significant changes are made to sentencing or release arrangements”.

The Prime Minister ordered a review of the early release scheme under the Sentencing Act shortly after taking office, but while changes were announced to prevent rapists and paedophiles being released early the measures did not cover Pc Harper’s killers.

The officer was fatally injured when he got caught in a strap attached to the back of a car and was dragged down a country road as the killers fled the scene of a quad bike theft in Sulhamstead, Berkshire, in 2019.

Two out of three of Pc Harper’s killers, Albert Bowers and Jessie Cole, are set to be released next year halfway through their 13-year sentences, after being convicted of manslaughter in 2020.

Before this year’s Sentencing Act, they would have served two-thirds of their term.

Mr Burnham previously said he had “pushed the very limits” in the changes he had made to the early release scheme, but has now said he can go further.