FRANKFURT (Reuters) - The sale of Germany's biggest retail bank Deutsche Postbank could fail because the price potential bidders are willing to pay does not meet the expectations of the lender's parent, Deutsche Post, a German magazine reported on Saturday.

Business weekly Wirschaftswoche cited sources close to Germany's Finance Ministry as saying that Deutsche Post, which owns a stake of 50 percent plus one share in Postbank, expected offers valuing the lender at more than 10 billion euros ($15.70 billion), but has received non-binding offers only of between 8 and 9 billion euros.

"For Post, that is too little," the magazine quoted an insider as saying.

Post's supervisory board is fixed on attaining a valuation in the double-digit billions of euros, the magazine said.

A Finance Ministry spokesman declined to comment and Deutsche Post was not immediately available.

The German government indirectly holds a 30 percent stake in Deutsche Post, giving it a say in the Postbank sale.

Finance Minister Peer Steinbrueck said in a newspaper interview earlier this week that he wants to find a merger partner for Postbank this year and prefers a German solution, though not at any price.

Deutsche Bank, Commerzbank and Allianz have flagged interest in Postbank, whose nearly 15 million-strong customer base makes it a major prize amid moves toward a broad consolidation among Germany's commercial banks.

Deutsche Post is also talking to foreign banks, including Spain's Santander, the UK's Lloyds TSB and Dutch bank ING, sources familiar with the matter told Reuters last week.

(Reporting by Jonathan Gould, Editing by Peter Blackburn)