The killers of PC Andrew Harper have had their sentences referred to the Court of Appeal after the Attorney General considered them to be “unduly lenient”.

Suella Braverman QC said attacks against emergency workers should be “punished with the greatest severity”.

PC Harper, 28, suffered catastrophic injuries when he was dragged behind a getaway car in Berkshire last August. Henry Long, Albert Bowers and Jessie Cole were convicted of manslaughter.

The driver, Long, 19, was jailed for 16 years while his passengers Bowers and Cole, both 18, were sentenced to 13 years each. The three teenagers were all cleared of murder charges following a trial at the Old Bailey in London. The Attorney General, Suella Braverman, said PC Harper’s killing was a “horrific crime which resulted in the death of a much-respected police officer while he was on-duty, protecting his community”.

She said she had referred the sentences after “having personally considered the details of this shocking case”. “Offenders should be punished with the greatest severity for such heinous crimes,” she added.

The referral comes after PC Harper’s widow Lissie and his mother Deborah Adlam launched campaigns calling for tougher sentences for killers of emergency service workers.

Reacting to the decision, Mrs Adlam said: “My family and I know that the whole nation stands with us in outrage at the sentences handed down to my son’s killers. “We can only hope that a fairer outcome is reached by the Court of Appeal to deliver the justice that Andrew deserves.”

Mrs Harper previously said she had received “many messages from people who are outraged” since the verdicts and sentences were handed down.

The maximum sentence a judge can impose for manslaughter is life imprisonment but they must specify a minimum term to be served. Mr Justice Edis, the sentencing judge in the case, told the Old Bailey each of the jail terms for PC Harper’s killers had to reflect “the seriousness of this case”.

A date for the hearing at the Court of Appeal has yet to be set.