FRANKFURT (Reuters) - The head of Volkswagen's <VOWG_p.DE> luxury unit Audi has been ordered to reimburse the car maker for the costs of a party that the car maker had initially paid for, a German weekly reported.

Audi Chief Executive Rupert Stadler has paid back 12,500 euros ($13,980) that he had expensed for a 'beer contest' with about 30 top managers in May 2015, after an internal revision reclassified the event as a private party, Bild am Sonntag reported.

Audi, where part of Volkswagen's defeat software was developed that lies at the heart of its emissions scandal, declined to comment on Sunday.

Expenses are a hotly debated matter in Germany, where the secretary of an industrial association was fired in 2009 after admitting to the theft of one meatball, while executives are often viewed as enjoying too many opportunities to expense private luxuries.

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(Reporting by Arno Schuetze; Editing by Adrian Croft)