Clifford was serving an eight-year jail sentence for historic sex offences
Former celebrity publicist Max Clifford has died in hospital after collapsing in prison in Britain.
The British Ministry of Justice said the 74-year-old had a heart attack after collapsing twice at Littlehey Prison in Cambridgeshire, where he was serving an eight-year jail sentence for historic sex offences.
A spokesman confirmed Clifford he died in hospital on 10 December.
"As with all deaths in custody, there will be an investigation by the independent Prisons and Probation Ombudsman," the spokesman said.
"Our condolences are with Mr Clifford's family at this difficult time."
Clifford's daughter Louise told the Mail on Sunday that her father first collapsed in his cell while he was trying to clean it on Thursday.
"It was just too much," she said.
"Next day he collapsed again and was unconscious for several minutes.
"He was seen by a nurse, who insisted he must be transferred to a local hospital.
"That's where he had his cardiac arrest, later on Friday."
Clifford was jailed in May 2014 after he was convicted of eight counts of indecent assault against four women between 1977 and 1984.
He had been arrested under Operation Yewtree, the Scotland Yard investigation launched in October 2012 after the late Jimmy Savile was exposed as a prolific paedophile.
Passing sentence at Southwark Crown Court, Judge Anthony Leonard told Clifford he had led a "double existence," living an outwardly respectable existence while grooming young girls for abuse.
During his PR career, Clifford's clients included boxer Muhammad Ali, singer Frank Sinatra, music mogul Simon Cowell and the late reality TV star Jade Goody.
He first came to the public's attention after creating the Sun's infamous headline "Freddie Starr Ate My Hamster" in 1986 - a story the publicist later admitted was a complete fallacy.
Clifford's first wife, Liz, died in 2003. His second wife, Clifford's former PA Jo Westwood, divorced him in 2014 following his indecent assault convictions.