Following his September DUI arrest, Michael Phelps will be barred from USA Swimming-sanctioned competitions for six months and will withdraw from next year’s FINA World Championships, USA Swimming said on Monday.

In a statement, USA Swimming Executive Director Chuck Wieglus said, “Membership in USA Swimming, and particularly at the National Team level, includes a clear obligation to adhere to our Code of Conduct. Should an infraction occur, it is our responsibility to take appropriate action based on the individual case. Michael’s conduct was serious and required significant consequences. Michael has publicly acknowledged the impact of his decisions, his accountability especially due to his stature in the sport and the steps necessary for self-improvement. We endorse and are here to fully support his personal development actions.”

“Michael accepts USA Swimming’s sanctions. He has apologized for his actions and, as he shared yesterday, is taking steps to address them,” said a rep from his management company, Octagon.

Phelps has undergone a six-week in-patient treatment program, according to Octagon.

The athlete said, “I’m going to take some time away to attend a program that will provide the help I need to better understand myself.”

Following his retirement following the 2012 Olympics in London, Phelps made his comeback to competition last year. Phelps earned what was expected to be the last of his 22 Olympic medals, the most by any athlete. When he announced his comeback, he stated that he planned to compete in the 2016 Olympic Games in Rio de Janeiro.

He revealed his decision to take a break on Sunday on his official Facebook and Twitter sites, saying: ‘I recognise 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.’

Phelps has been arrested for DUI twice in the last 10 years. Phelps was sentenced to 18 months of probation for a previous incident when he was 19 years old.

After images surfaced in 2009 that purported to show Phelps consuming marijuana, he was suspended for three months.

In a statement posted Monday, USOC CEO Scott Blackmun deemed the fines “appropriate”.

“We are glad that Michael is seeking help. We are grateful that nobody was hurt and appreciate the speed at which USA Swimming and Michael took action,” the statement said.