WASHINGTON (AFP/REUTERS) - Michael Phelps, the 18-time Olympic swim champion arrested last week for drink driving, has been banned for six months and dropped from the 2015 FINA World Swimming Championships roster in Russia next August,

The punishments, handed down by USA Swimming on Monday, came six days after Phelps, the most decorated Olympian of all time, was apprehended by police in his hometown of Baltimore and charged with driving under the influence of alcohol, excessive speed and crossing the centre line while driving inside a tunnel.

Phelps had recently returned to top-level competition after a two-year retirement.

On Sunday, Phelps said on Twitter that he would be taking a break from swimming and "take some time away to attend a program" for treatment of unspecified issues.