United States swimmer Michael Phelps has announced that he will take a break from the sport in order to overcome personal issues.

The 29-year-old, who is the most successful athlete in Olympic history with 18 gold medals to his name, was charged with drink driving in his home state of Baltimore last week.

"The past few days have been extremely difficult," Phelps said in a statement. "I recognize that this is not my first lapse in judgement, and I am extremely disappointed with myself.

"I'm going to take some time away to attend a program that will provide the help I need to better understand myself.

"Swimming is a major part of my life, but right now I need to focus my attention on me as an individual, and do the necessary work to learn from this experience and make better decisions in the future."

Phelps initially retired from swimming in 2012, only to make a return to the pool earlier this year.