Channel 4 has announced a one-off documentary about the late PR mastermind Max Clifford.

The publicist - known during his lifetime for holding the keys to the entertainment world's biggest secrets - was convicted to eight years in jail for a string of sex offences in 2014 and died three years later at the age of 74, having suffered a heart attack behind bars.

The 90-minute film, The Max Clifford Story, will feature excerpts from 30 hours of previously-unheard audio tapes of Clifford, as well as "devastating testimony" from some of his victims, who will be talking publicly for the first time.

"Story Films have used fine journalistic skills to uncover new material that sheds fresh light on the man who was hailed as the king of the celebrity-focused press and, as such, seemed untouchable," said C4 factual commissioner Sacha Mirzoeff.

"With skilful storytelling and strong testimony from a variety of friends, colleagues and victims they start to reveal and unravel the mind of the convicted sex offender who was one of the most powerful and complex public figures of his generation – full of contradiction, self-importance and myth-making.

"This extraordinary feature length single film uncovers the true consequences of his actions."

The piece comes from Story Films, who are also working on The Real AC-12 for Channel 4 and The Premiership: A Whole New Ball Game for BBC Two.