A Northland club rugby team is being boycotted by its competition, who are claiming gang members associated with the club are threatening them with violence.

Five rugby clubs have refused to play against the Whangaruru second division team, as some of its players are patched Head Hunters.

Northland Rugby Union CEO Jeremy Parkinson said there have been claims Head Hunters gang members associated with the club have threatened other teams and supporters on the field and after games, "in the clubroom and in carparks".

Parkinson said it's a difficult situation because the team hasn't breached any codes or ethics on the field and has received only two yellow cards this season.

The Northland Rugby Union has enlisted the help of the NZRU and will launch a full review of the claims.