STUTTGART/HAMBURG, Germany - Porsche SE on Thursday refused to cede victory to Volkswagen in a test of wills over who will control the automotive juggernaut the German carmakers aim to forge.

Dismissing reports that Porsche's owner clans had finally settled the power struggle, Porsche Deputy Chairman Uwe Hueck said he had been promised by the two families that they would make no decisions before consulting Porsche's supervisory board.

A source close to Volkswagen told Reuters the families had struck a deal in principle that would let Europe's biggest carmaker absorb debt-laden Porsche's healthy sports car business, initially by buying a 49.9 percent stake in Porsche AG.

That would hand victory to VW Chairman Ferdinand Piech, who has been pushing such a deal for months as a way to add a 10th brand to his sprawling automotive empire that ranges from tiny VW models to high-end Bugattis and Lamborghinis to heavy trucks.

It would also mark a setback to Piech's cousin Wolfgang Porsche -- the chairman of Porsche SE who with his Chief Executive Wendelin Wiedeking has rejected such a sale.

VW had won over Wolfgang Porsche, the source said, adding the issue now was persuading Porsche management to go along with a plan that would undercut Wiedeking's authority.

Selling a Porsche AG stake remains an option, Hueck told reporters, but added that he and Wiedeking preferred to strengthen the group's balance sheet by issuing new shares and selling a stake to a Qatari investment fund.

Hans Michel Piech and Wolfgang Porsche have given me their word that the families will not decide anything without discussing it with the supervisory board, said Hueck, who is Porsche's top labour leader.

Hans Michel Piech is Ferdinand's brother and a Porsche board member.