All Black and Crusaders winger Zac Guildford is being investigated by the New Zealand Rugby Union which could lead to him having his contract terminated.

Guildford has voluntarily stood down from his Super Rugby team, the Crusaders, after approaching management and admitting he was involved in an incident during a house party last weekend.

The winger has a history of alcohol-related issues and in the last 18 months has been called before the New Zealand Rugby Union three times.

New Zealand Rugby Union chief executive Steve Tew says that the Crusaders and the NZRU were "very disappointed'' to learn of the incident involving Guildford at the private house party.

"As a result, the NZRU has initiated misconduct proceedings against Zac,'' Tew told AAP.

"We will be meeting with Zac and his representative in the following week to discuss the matter, and next steps."

Guildford's misconduct last year kept him out of the Crusaders pre-season matches as well as their opening Super Rugby match in 2012 after he was suspended for four weeks having assaulting two bar patrons during a drunken episode in the Cook Islands capital, Raratonga.

The nature of the current incident has not been revealed but New Zealand Rugby Union chief executive Steve Tew confirmed that a misconduct process was underway.