Zayna Iman told Sky News the incident took place while she was held by officers from Greater Manchester Police.

The 38-year-old's allegation is supported by her medical records, which show evidence of sexual injuries.

Responding to the Independent Office for Police Conduct (IOPC) investigation, Ms Iman told Sky News: "I've been dealing with the whole police complaints procedure since 2021. I've been gaslit, I've been stonewalled. And as a last resort, I waved my right to anonymity and that wasn't easy."

She said she had been "failed by the entire police complaints procedure" and had "zero faith" in the investigation and the justice system.

The IOPC said it had received two referrals from Greater Manchester Police on Wednesday 26 July 2023 linked to complaints made by the woman regarding her detention by officers at Pendleton Police Station in February 2021.

They said one was a "re-referral of matters we originally received" back in May 2022, while another "contained new allegations regarding the woman's treatment in custody that had not previously been brought to our attention".

Investigation will look at 'nature of interaction' woman had with police in custody

IOPC regional director Catherine Bates said: "These very serious allegations will have undoubtedly unsettled the local community and the wider public. Their severity raises understandable concern and has the potential to undermine confidence in policing.

"In light of the new information we recently received and the significant media attention generated, as well as a request from GMP, we have taken the decision that an independent investigation is required into the allegations."

Ms Bates said the IOPC was "aware of footage of the woman's detention" and said the investigation "will be thorough and independent of the police".

She said the investigation "will look at the nature of the interaction the woman had with police while in custody and allow us to understand what happened on the night in question".

'I believe a lot of evidence has been lost'

Former GMP chief superintendent Martin Harding has seen the available footage and said Ms Iman's claims are credible.

Describing how the IOPC investigation would progress and its potential pitfalls, he said: "The first thing they've got to do is go back to day one and start to see what evidence is out there for them to gather.

"That's a key part of an investigation. And I'm afraid I believe a lot of evidence has been lost.

"What they've then got to do is interview key witnesses, but the problem they've now got is a lot of these witnesses, their memory is two and a half years on, they've slept a lot and they've had a lot of cases in between.

"So will we get a true reflection of what took place back in those days?"

Missing CCTV footage

CCTV footage shows Ms Iman being carried into a police cell unconscious and with her hands cuffed behind her back.

It appears to show her being forced face-down onto a thin mattress before police officers take off her jeans, cut off her knickers, pull a pair of oversized custody shorts over her legs and then remove her top and bra before leaving her alone and topless.

Police arrested Ms Iman in the early hours of 5 February 2021 at her home after she knocked the glasses off a female officer's face. They were following up on a welfare callout over a woman high on cocaine.

Over the next 40 hours or so, Ms Iman - who has waived her right to anonymity - would be taken to and held at a police station. From that period, there are at least two hours of missing footage which GMP have so far failed to supply.

GMP has said the CCTV footage from the custody cell was burnt on to four discs in hour-long segment but one disc corrupted and it was identified that two hours were missing.

The force has added there is currently no evidence to suggest any employees have misconducted themselves or committed a criminal offence.

GMP said it would be inappropriate to comment on an IOPC investigation.