A police crackdown on "tinnie houses" has revealed a mortgage broker, nurse and train driver among the customers for illegal drugs.

Since Operation Beware was launched in the Auckland suburb of Otara two weeks ago 40 drug purchasers had been arrested and charged, Inspector Jim Searle said.

The recent arrests included professionals, mothers and tradespeople.

"Amongst those arrested were a train driver, a mortgage broker, a nurse, several students and qualified tradespeople," Mr Searle said.

Police were working on ways of informing employers about staff member arrests, as it was believed many people were buying drugs in work time and may be unsafe in their jobs when affected by drugs.

"Some people are visiting tinnie houses during the day and in company vehicles when making their purchases."

Many of the people arrested did not have previous criminal records and Mr Searle wanted to warn potential purchasers they risked carrying a criminal history for the rest of their lives.

The operation was launched in response to a public call for zero tolerance of gangs and their illegal activity in Otara, Mr Searle said.

Police wanted to take Otara off the map as a destination known for drug houses, and instead wanted it known as somewhere people would be arrested if they tried to buy cannabis or methamphetamine, he said.

"Purchasers of illicit drugs are coming in large numbers from Auckland City, Waitemata and as far away as New Plymouth, Huntly and Tauranga," he said.

Operation Beware will continue in the coming weeks.

- NZPA