BERLIN (Reuters) - Former Volkswagen VOWG_p.DE Chairman Ferdinand Piech has agreed to sell a major part of his stake in the firm that controls Europe's biggest carmaker, reducing his links with Volkswagen after more than two decades of undisputed rule.

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Volkswagen's (VW) ruling Porsche and Piech families have agreed to buy a large part of the 14.7 percent stake Piech holds in Porsche Automobil Holding SE PSHG_p.DE, which in turn owns 52.2 percent of voting shares in VW, exercising their right of first refusal on the shares, Porsche SE said on Monday.

It did not say exactly how much of the stake the families would buy and gave no details on the price. Piech’s total stake in Porsche SE is worth about 1 billion euros ($1.1 billion) at current market prices.

The withdrawal from Porsche SE of Piech, who turns 80 on April 17, had been expected after the company said last month he was in talks about selling his holding.

It marks an end to the influence of one of the last towering figures in the auto industry, who has had a rocky relationship with VW since he was ousted as chairman in 2015, months before the company was engulfed in an emissions test cheating scandal.

An industrial scion and engineer, Piech transformed VW from a regional carmaker into a global powerhouse which during his reign bought the luxury Bugatti, Bentley and Lamborghini brands and integrated the mass-market Skoda and Seat businesses.

The grandson of Ferdinand Porsche, founder of the sports car maker that developed the classic VW Beetle under a 1934 contract with the Nazis, Piech led VW as chief executive from 1993, and later as chairman.

But since quitting as chairman in April 2015 following a power struggle with former CEO Martin Winterkorn, he has become a recluse and unwilling to defend the empire he helped build.

In that struggle, Piech’s billionaire cousin Wolfgang Porsche, the chairman of Porsche SE, sided with Winterkorn, as did other top players on VW’s supervisory board.

A media report in February said Piech had told investigators that his cousin and other VW board members knew about the emissions test cheating earlier than stated in public - something VW has denied. That led some members of the Porsche and Piech clans to want to eject Piech from the supervisory board of Porsche SE, a source at the holding company has said.

Porsche SE said on Monday Piech would stay on the board until the closing of the stake sale, which requires regulatory approval. Piech’s Ferdinand Karl Beta foundation will retain a minor stake in Porsche SE, it added, without elaborating.