Auckland Mayor Len Brown says Sky City Casino is not doing enough to help problem gamblers.
Mr Brown says new figures from the Gambling Commission show a tripling in the number of problem gamblers identified at the casino in the past three years.
They also show the casino's exclusions of problem gamblers increased by only a quarter in the same period.
Mr Brown is also concerned by reports that a host responsibility programme at Sky City has never been reviewed, despite its license requiring that to happen every two years.
He says the casino must do a better job if it wants to be allowed to operate more gaming machines in return for a convention centre in Auckland.
He urges the introdution of harm minimisation officers on site 24 hours per day, pre-paid cards to limit expenditure and harm minimisation screen savers, which display before gaming begins and when someone wins.
