The personal information of 1,230 people including victims of crime and witnesses was included in Freedom of Information responses issued by Norfolk and Suffolk Police, the forces said.

On Tuesday, the constabularies issued a joint statement, explaining they had identified an issue with “a very small percentage of responses to Freedom on Information requests for crime statistics” between April 2021 and March 2022.

Due to a technical issue, raw data relating to crime reports was included in the FoI responses.

It includes personal identifiable information on victims, witnesses, and suspects, as well as descriptions of offences, the constabularies said in their joint statement. “It related to a range of offences, including domestic incidents, sexual offences, assaults, thefts and hate crime.”

The data was not visible to anyone opening the files, but “it should not have been included”, they said.

The police are currently notifying those whose data was breached, with a total of 1,230 people being contacted via mail, telephone or face-to-face depending on the severity of the breach.

“Within the notification, people will be provided with all the necessary information including what personal data specific to them has been impacted and details of who they can contact for support,” the statement read.

Assistant Chief Constable of Suffolk Police, Eamonn Bridger, who led the investigation on behalf of both forces, apologised for the leak, adding that procedures for handling FoI requests made to the constabularies “are subject to continuous review to ensure that all data under the constabularies’ control is properly protected”.

The Information Commissioner’s Office said it is currently investigating this breach as well as a separate breach reported in November last year.

The deputy commissioner Stephen Bonner said: “It’s too soon to say what our investigation will find, but this breach – and all breaches – highlights just how important it is to have robust measures in place to protect personal information, especially when that data is so sensitive.

“We are currently investigating this breach and a separate breach reported to us in November 2022,” Mr Bonner added. “In the meantime, we’ll continue to support organisations to get data protection right so that people can feel confident that their information is secure.

This leak comes just days after a major data breach involving personal details of every officer of the Police Service of Northern Ireland (PSNI) triggered fears for their safety.

Deputy chief constable Chris Todd confirmed the names, ranks, and other personal data “for each of our current employees across the police service” had been mistakenly divulged in response to a “routine” FoI request.

The data was posted on the site WhatDoTheyKnow for a short period of time before being taken down.

Mr Todd said said the severe terrorist threat facing PSNI officers has made news of the extensive data breach “the last thing that anybody in the organisation wants to be hearing”.

After news of the breach broke, PSNI chief constable Simon Byrne said he is confident that information on police officers and civilian staff mistakenly was in the hands of dissident republicans.

At a press conference in Belfast, Mr Byrne said he believed they would use the information to intimidate and target police.

Additional reporting on agencies.