The chief executive of the New Zealand Rugby Union says racial abuse directed at Auckland Blues coach Pat Lam is appalling.
The Blues have won just one of their six games so far and languish at the bottom of the Super Rugby competition.
The team's performance has prompted comments on social media sites and talkback radio that Lam's Polynesian background is to blame.
On Wednesday Mr Lam broke down in tears as he spoke of the racial abuse he and and his family have been subjected to.
NZRU chief executive Steve Tew says people who hide anonymously on social media while making such comments will not be tolerated.
Auckland Rugby Union chief executive Andy Dalton says this type of criticism of the coach for the team's poor season is gutless and has to stop.
Mr Dalton told Radio New Zealand's Morning Report programme that racist comments have been appearing on the team's website and it shows an ugly side of society.
Crusaders coach Todd Blackadder says while coaches expect criticism when their teams do not perform well, making racist comments is uncalled for.
He says the comments are disgraceful and people who make them should front up and put their name to them.
Mr Blackadder says racism should not be tolerated and the World Cup-winning All Black side is a good example of New Zealand's multi-cultural society.