CHICAGO (Reuters) - Speedo extended its sponsorship deal with gold medal-winning swimmer Michael Phelps through 2013, the swimwear company said on Wednesday 9 September.

Terms of the four-year deal were not disclosed. Last summer, Phelps was reported to be earning about $5 million a year from his combined endorsements.

With 14 Olympic gold medals, Phelps, 24, has won more than anyone else after his eight at the Beijing Olympics last summer. Speedo, which has sponsored Phelps since 2001, awarded him a $1 million bonus for breaking Mark Spitz's record of seven gold medals at the Munich Games in 1972.

"Michael has transformed the sport of swimming, with more fan interest and participation than ever before," Joe Gromek, CEO of Warnaco Group Inc, North American licensee for the Speedo brand, said in a statement.

Warnaco distributes almost half of Speedo gear globally.

(Reporting by Ben Klayman, editing by Maureen Bavdek)