Michael Phelps has apologized after a controversial photo that apparently shows him inhaling from a marijuana pipe was published in a British newspaper Sunday.

"I engaged in behavior which was regrettable and demonstrated bad judgment," the all-time Olympic swimming champ said Sunday in a statement released by his marketing agency, Octagon.

"I'm 23 years old, and despite the successes I've had in the pool, I acted in a youthful and inappropriate way, not in a manner people have come to expect from me. For this, I am sorry. I promise my fans and the public it will not happen again."

The photo published in News of the World and his admission are not likely to affect Phelps's eligibility to compete, though it remains to be seen what this could mean to his millions of dollars in endorsement deals.

The U.S. Olympic Committee also issued a statement Sunday. It said: "We are disappointed in the behavior recently exhibited by Michael Phelps.
 Michael is a role model, and he is well aware of the responsibilities and accountability that come with setting a positive example for others, particularly young people.

"In this instance, regrettably, he failed to fulfill those responsibilities. 
Michael has acknowledged that he made a mistake and apologized for his actions. 
We are confident that, going forward, Michael will consistently set the type of example we all expect from a great Olympic champion."

When he was 19, in 2004, just before winning six gold medals and two silvers at the Athens Olympics, Phelps also swam into hot water – and pleaded guilty to a drunken driving charge. He also apologized at the time.