FRANKFURT - The Porsche and Piech families will hold around 45-55 percent stake in an entity to be formed from a planned merger between Europe's biggest carmaker Volkswagen and Porsche, according to a German weekly magazine, citing sources.

The federal state of Lower Saxony will own around 21-25 percent stake in the new company, Der Spiegel said in its pre-release on Saturday.

The concept, which is being worked out by Deutsche Bank and Goldman Sachs, is still open and it is unclear whether it will be implemented, the report added.

It noted Lower Saxony Premier Christian Wulff, whose state owns a blocking minority vote of around 20 percent in VW, is not prepared to absorb the financial risks of Porsche company through the merger with Volkswagen.

Focus weekly magazine, also citing sources, said in its pre-release on Saturday that Lower Saxony and another investor could own around half of the new combination while the Porsche and Piech families between them would own the rest.

Focus said a possible investor in the merged entity could be the Emir of Qatar.

It said Rupert Stadler, currently Chief Executive of VW unit Audi (NSUG.DE), could become a compromise candidate and emerge as the new Chief Executive of the new company.

A spokesman for Porsche declined comment on the reported shareholdings as well as on who would be the new CEO but said: The negotiations should start next week.

A spokesman for VW declined comment.