Olympic swimming champion retires

German swimmer Britta Steffen, who won gold in the 50 and 100-meter freestyle at the 2008 Beijing Olympics, has announced her retirement.

The 29-year-old Steffen said in a statement on Friday from her management that she was ending her career "in the knowledge of being one of the best in the world."

However, Steffen said she doubted over recent weeks whether she could "muster the necessary motivation and energy for one or even three more years in the fight for gold medals and championship titles," news agency dpa reported.

Steffen followed her Olympic wins in Beijing with world championship gold medals in the same events a year later in Rome.