UPDATED 2.32PM: The arrest of former All Black Mils Muliaina has come as a huge shock, according to a rugby commentator at the scene of the arrest.

Muliaina was arrested on suspicion of an alleged sexual assault that took place in Cardiff in March.

He was arrested in Gloucester this morning New Zealand time, after his Irish club team Connacht was defeated by the local side.

LISTEN: Michael Corcoran - Muliaina Arrested

He was led away from the ground and put in a police van shortly after the match ended while live sports cameras filmed the post-match situation.

Commentator Michael Corcoran said everyone at the game was in shock.

"Gloucestershire constabulary came into the dressing room area straight after the game and has been taken away and was taken away in a police van for questioning about an alleged assault which took place in Cardiff in March."

Corcoran said police made the arrest on behalf of South Wales authorities, who are handling the investigation.

In 2010, he underwent open-heart surgery to patch a small hole in his heart.

In his early career with the Blues, Muliaina courted controversy when he was suspended from two NPC games after urinating in a Parnell bar.

A year later he and fellow Blues player Doug Howlett were involved in a scuffle outside nightclubs in Auckland's waterfront, in which Muliaina suffered a bruised and bloodied face.