BERLIN (Reuters) - Former Volkswagen (>> Volkswagen AG) chairman Ferdinand Piech is in talks to sell his stake in Porsche SE (>> Porsche Automobil Holding SE) in a deal that would shake up the ownership structure of the company that controls VW.

Porsche SE is the group through which the billionaire Porsche and Piech families control 52.2 percent of the voting shares in Volkswagen (VW), which is still dealing with the effects of its diesel emissions scandal.

The families are in negotiations to buy a substantial part of Ferdinand Piech's 14.7 percent stake in Porsche SE, Porsche SE said in a statement on Friday, confirming a report by weekly magazine Der Spiegel.

"At present, it is still unforeseeable whether the aforesaid changes in the shareholder structure of Porsche Automobil Holding SE will in fact occur," the group said in a statement in English.

Volkswagen declined to comment.

The Porsche and Piech families have a right of first refusal on Porsche shares held by Piech, which are worth just over 1 billion euros ($1.1 billion) based on current market prices.

If Piech, who turns 80 next month, were to sell his stake, it would mark the end of an era for Volkswagen which he dominated for decades. An industrial scion and engineer, he transformed VW from regional volume manufacturer into a global powerhouse, which owns the Bentley, Bugatti, Skoda, Lamborghini, Porsche, Seat and Audi brands.

The grandson of Ferdinand Porsche - founder of the sports car maker that developed the Beetle under a 1934 contract with the Nazis - Piech turned around VW as chief executive, from 1993, and later as chairman. But since resigning as chairman in April 2015 following a showdown with former CEO Martin Winterkorn, he has become a recluse and unwilling to defend the empire he helped build.

"Piech had no more chance to crown his life's work and has lost most of his allies," said Ferdinand Dudenhoeffer, head of the Center of Automotive Research at the University of Duisburg-Essen. "Selling off his stake is the most logical step."

Dudenhoeffer said he doesn't expect the Porsche-Piech families to put up the financial means to fund the buyout and instead expects industrial investors like VW's two Chinese joint venture partners FAW Group Corp and SAIC Motor Corp Ltd (>> SAIC Motor Corporation Limited) to seize the opportunity.

Porsche SE shares closed down 1.8 percent at 50.96 euros on Friday, after briefly gaining 20 cents after Porsche's statement, while VW shares closed 1.3 percent lower at 138.40 euros, but had jumped about 30 cents after the statement.

Piech's withdrawal may also raise investor hopes that the group can finally overcome what many analysts have dubbed a dysfunctional structure, which has seen the group hamstrung by the carmaker's powerful labor unions and the state of Lower Saxony, which holds a blocking minority with its 20 percent stake.

"Should industrial investors step in, this could create double pressure for change from owners and investors," said Dudenhoeffer. "For VW, it could be a chance, at last, to free itself from the strangling grip of the unions and Lower Saxony."

An unsourced media report said last month that Piech had already begun attacking his former allies and had informed top directors about potential cheating of diesel emission tests six months before the scandal became public in September 2015.

VW has strongly denied this and last month signaled it could take legal action against Piech.

Bild am Sonntag separately reported earlier this month that Piech could lose his supervisory board seat at Porsche SE, his only remaining position at the group.

(Reporting by Andreas Cremer; Writing by Maria Sheahan and Edward Taylor; Editing by Susan Fenton)