An expert witness has allegedly suggested that police videos of the Hillsborough disaster may have been edited after the event, a pre-inquest hearing has heard.

A barrister representing several families who lost loved ones in the tragedy told the hearing that the expert had studied footage taken on a hand-held camera inside the football stadium, and concluded that it may well have been edited at a later date.

It also emerged that 74 more Hillsborough-related police statements are suspected of being altered than originally thought – a figure that would suggest a far wider cover-up of the disaster.

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238 police officers are accused of tampering with official statements in the aftermath of tragedy, but only 57 of the 220 that are still alive have been interviewed by the Independent Police Complaints Commission.

Steven Kelly, who lost his brother Michael in the Hillsborough disaster, told Sky News: “It's so shocking. Every new inquest into Hillsborough there is new evidence which suggests a cover-up.”

He added: “It’s interesting today to hear of the amount of police notebooks which were tampered with and allegations that cameras have been tampered with. It’s frightening, really… I'm pleased the legal team have found this new evidence and I'm sure they'll get the right experts to find out if they have been tampered with”.

Mr Kelly went on to say: “Looking at Lord Justice Goldring's performance today, he’s truly got a grip on it and is determined to run the inquest his way. I have total confidence in him and our legal team to get to the bottom of it.

The IPCC hopes to complete all police interviews by February 2014 before the new inquest begins in March. The inquest will be held in Warrington in front of a jury and is expected to last six to nine months.