Michael Phelps comes out of retirement

American swimmer Michael Phelps has come out of retirement ahead of a possible return to the pool for the 2016 Rio Olympics.

The 22-time Olympic medallist will compete for the first time since the 2012 London Games when he takes part in a meet in Arizona at the end of the month.

The 28-year-old re-entered the USA's drug-testing program last year and is now eligible to compete again after a six-month waiting period.

Phelps has 18 Olympic gold medals to his name, while he has also picked up two silvers and two bronze during the past three Games.