Adidas Group will seek arbitration over a contract to be the official supplier to the German Football Association, following a EUR500m (US$660m) rival offer from Nike.

The company believes that its existing supplier agreement with the association was "effectually extended" in August 2006 until at least 2014, and is seeking confirmation.

Adidas said: "In the past months, Adidas has made every effort to find an amicable solution with the German Football Association DFB.

"Unfortunately, we were not able reach an agreement. In order to achieve an objective decision in a timely manner, we have decided to take this matter to arbitration, as stipulated in our existing contract with the DFB."