Mils Muliaina said he had "no idea" he was about to be arrested after his match on Friday.
The New Zealand Herald reports that the Connacht rugby star thought he was being pulled aside for a drugs test, when police took him into custody over a sex assault on Friday, citing his manager as a source.
The 34-year-old former All Black was escorted into a police van minutes after he finished a challenge Cup match against Gloucester.
He was released yesterday on bail.