FRANKFURT, June 14 (Reuters) - Sportswear maker Adidas (ADSG.DE) is making significant progress in restructuring its U.S. brand Reebok, Adidas Chief Executive Herbert Hainer told German newspaper Welt am Sonntag on Sunday 14 June.

Nicole Vaidisova for Reebok

"We are making significant progress with Reebok," he said when asked whether Adidas was considering selling Reebok, though he added that the restructuring was not proceeding "fast enough".

Adidas bought Reebok in 2006 to boost its position in classic sportswear and help it better compete against Nike (NKE.N).

Hainer said Adidas wants to grow its Outdoor brand on its own, adding Outdoor sales have grown by a two-digit percentage this year.

He said Adidas is investing in Outdoor and has recently renewed its partnership with Reinhold Messner, with an agreement to intensify cooperation in product development, among other things.

Adidas launched its Outdoor brand in 2007.

Hainer said Adidas would hardly be affected by the problems of insolvent Arcandor's (AROG.DE) Karstadt department store chain.

Adidas had limited its trade credits to Karstadt and has already stopped deliveries to it.

Hainer said the number of department stores may fall in Germany in the end but many small sporting shops would remain open.

He said Adidas would continue to open its own shops.