"Following a calf injury suffered on July 5, I shall not be able to train for the Olympic Games," the 34-year-old French athlete said in a statement issued by the French federation.
"As I had already decided that the 2004 season would be my last season, I have decided to end my career as an athlete."
Diagana won the one-lap hurdles gold medal at the 1997 Athens world championships and the European title in 2002.
He has held the European record of 47.37 seconds since 1995.
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