A total of 132 police officers and staff have not assisted the police watchdog’s investigation into the Hillsborough disaster.

The Independent Police Complaints Commission (IPCC) is looking at whether offences such as conspiracy to pervert the course of justice and perverting the course of justice were committed in the aftermath of the 1989 disaster.

In her latest update, IPCC deputy chair Rachel Cerfontyne said: “The investigation is continuing to contact a number of police officers and staff who have not assisted our investigation so far.

“In total there are 132 officers and staff who have been approached, but have not provided a witness account; 64 are from South Yorkshire police and 68 are from West Midlands police (WMP).

“Some were unable to provide an account for reasons such as poor health; others have not responded to our contact and there are a number of individuals who couldn’t be traced.”

She said the above potential witnesses had been identified because they may have useful information and that further efforts would be made “to persuade this group to engage with us”.

Cerfontyne pointed out the IPCC could compel serving police witnesses to attend an interview, but not retired officers.

She added: “The majority of police witnesses we have approached have helped us. We have recorded over 4,000 witness accounts during the course of the investigation and around 1,200 of those are from police officers or staff.”

A separate criminal investigation, Operation Resolve, is looking at the lead-up to the crush and the match day itself, with offences considered including gross negligence manslaughter, misconduct in public office and various health and safety breaches.

Both inquiries remain on track to deliver full files of evidence to the Crown Prosecution Service at the end of this year.

In April, a jury at the fresh inquests into the deaths of the 96 Liverpool fans concluded they were unlawfully killed and that blunders by South Yorkshire police “caused or contributed to” the disaster at Sheffield Wednesday FC’s stadium.