New Zealand and Crusaders winger Zac Guildford has issued an apology after allegedly assaulting two men at a bar.

The 2011 Rugby World Cup winner was accused of the attacks at Trader Jacks bar on the island of Raratonga on Thursday.

Bar owner Jack Cooper said Guildford arrived at the bar drunk, naked, dripping wet and bleeding from a cut to the forehead, before punching two men.

"Firstly, I would like to apologise for my behaviour here in Rarotonga on Thursday night," Guildford said in a statement.

"I have no clear recollection of the events of that night but there is no doubt that my behaviour was unacceptable and I am hugely embarrassed by what happened.

"I want to apologise to the people who I was involved with and offended that night, the patrons and staff who witnessed my behaviour, and the Cook Island people. I am truly sorry for what I did.

"It's obvious that I need help and I want to get home and to get that help as soon as I can. I need to sort myself out."

Guildford scored four tries for the All Blacks during their 2011 World Cup campaign.