A statement from Gloucestershire Police to The Independent read "A man in his 30s was arrested at Kingsholm Stadium tonight on suspicion of an alleged sexual assault in relation to an incident in Cardiff in March. It is a matter being dealt with my South Wales Police."
Connacht Tribune rugby media advisor Rob Murphy said the spokesperson for the club would not comment about the incident.
"There is a general sense of shock here and Connacht officials seem as stunned as we are. (Connacht coach) Pat Lam spoke but took no questions about the incident," said Murphy.
The arrest 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.
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.
Irish rugby commentator Michael Corcoran was at the game when Muliaina was arrested and told Newstalk ZB Muliaina and former All Black John Afoa had passed him in the tunnel as players were coming off the pitch.
"The two of them were cracking the yarn, laughing and joking as all mates do."
He said there was no sign anyone was aware of the imminent arrest.
"It came as a huge shock... they didn't know why he had been taken away."
Corcoran told Newstalk ZB that the post-match press conferences had been held before the arrest was made, and current Connacht coach, former Blues coach, Pat Lam didn't mention anything about the alleged incident.
"They certainly weren't aware of it at the time," Corcoran said.
"It's a situation that caught everybody by surprise."
Corcoran said this was probably the first time Muliaina had been back in the United Kingdom since the alleged incident in Wales in March, and he assumed that was why the police made the move to arrest him at the ground.
A statement from Gloucestershire Police to The Independent said: "A man in his 30s was arrested at Kingsholm Stadium tonight on suspicion of an alleged sexual assault in relation to an incident in Cardiff in March. It is a matter being dealt with my South Wales Police."
Connacht Rugby issued a statement to media to confirm Muliaina was assisting South Wales Police with enquiries related to an alleged incident in Cardiff in March.
The club said it would comment further.
Muliaina has 100 caps for the All Blacks between 2003 and 2011, and was the second All Black to make that milestone.
The Samoan-born fullback joined the Connacht team last year, and announced earlier this week he would be leaving the Irish club for Italian side Zebre at the end of the season.
Muliaina is married to wife Hayley, and has a 6-year-old son Max.
In 2010, Muliaina spoke of the difficult time he and his wife went through when Max was two months old and 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 in 2002.
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. He initially laid a complaint with police, but the case never made it to court.
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Connacht coach, Former Auckland Blues' coach Pat Lam, who refused to speak about the alleged incident involving Muliania said; "We gave away a couple of soft tries, but we kept coming and coming in the second half and I'm very proud of the boys.
"We are a young group and we will learn a great deal from this. We will be a better team and I think the experience of coming here will help us."
The exact date of the assault is not known.
More to come.
