The Department of Internal Affairs says casinos are high-risk targets for organised crime.
This follows news of a multi-million dollar drug syndicate having operated within Auckland's SkyCity Casino.
The gang's ringleader, Ri Tong Zhou, who has been jailed for 15 years, is said to have used the casino's VIP lounge as his office.
Internal Affairs director of gambling compliance Mike Hill says casinos like SkyCity are particularly at risk and should be extra-vigilant when high-rollers are using their facilities.
SkyCity Casino chief executive Nigel Morrison says the casino adheres to the highest standards of gaming surveillance and compliance, and takes any issues relating to illegal activity extremely seriously.
Mr Morrison says the Zhou case happened more than two years ago, and SkyCity was just one of a number of venues used.