Family feuds may best be played out behind closed doors, but Sumner Redstone, the 84-year-old billionaire chairman of Viacom and CBS, has decided to ignore such wisdom.

His differences with his daughter, Shari, are being aired on a public stage, against the backdrop of a media empire that takes in MTV, Paramount Pictures and Comedy Central.

The spotlight on the Redstone family intensified this week after it emerged that its patriarch was trying to sideline Shari, the non-executive chairman of both CBS and Viacom.

Ms Redstone, 53, also runs the National Amusements cinema chain, which includes 19 Showcase cinemas in Britain.

Mr Redstone, the man credited with the expression “content is king”, has often said in the past that his daughter was “likely” to succeed him as chairman of Viacom and CBS.

However, their relationship began to deteriorate about a year ago as Paula, his 45-year-old wife, raised already simmering tensions over the running of the cinema chain. Mr Redstone’s relationship with his daughter became so strained that there were times last year when they would communicate only by fax. More recently, their contact has been confined to their legal representatives, as they seek to hammer out a settlement.

A spokeswoman for Ms Redstone acknowledged that father and daughter had had “limited contact” in recent months, but denied that any changes in her role were in the pipeline. However, the talks are expected to lead to Ms Redstone’s departure from the boards of Viacom and CBS, which split in January 2006, along with the sale of her stake in the family empire. In return, she would become the sole owner of the cinema chain, which has 100 outlets in the United States, Latin America, Russia and the UK. It was founded by her grandfather as the first plank in the family empire.

The dispute stems from Ms Redstone’s desire to expand the National Amusements chain. Her father wanted to cash out of the business and expand in areas such as casinos, which he believed offered far better growth potential.

Mr Redstone, who is fond of asserting unchallenged authority, is also thought to have been infuriated by his daughter’s growing involvement in CBS and Viacom and her public challenges to his strategy, as she has sought to emerge from her father’s shadow.

Against this backdrop, Paula, whom Mr Redstone had divorced his wife of 50 years to marry, is said to have engineered the move to oust Shari, who resented her new stepmother.

The new Mrs Redstone is no stranger to influencing management reshuffles in her husband’s group. Mr Redstone has acknowledged that his decision to drop Tom Cruise, the actor, from Paramount Pictures last year, apparently without consulting his army of lieutenants, was taken on the counsel of his wife.

Mrs Redstone is said to be an ally of Philippe Dauman, Viacom’s chief executive, a fact that could become increasingly relevant as leading executives continue to jostle for position in the race to take over the empire when Mr Redstone dies.

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