"We believe that property is definitely an area where money laundering is taking place. We want to regulate ourselves and put in place safeguards.
"It's quite hard to track but we see this as a deterrent. There have been instances where people have tried to pay deposits with cash."
Ms Milne said REINZ had persuaded its members against taking cash deposit payments and encouraged them to ensure money was deposited into bank accounts.
Lawyers already collected identification details but agents would now require ID such as a passport or driver's licence.
"We know it's something that's been tightened up across other industries."
Asked if the risk of money laundering was from particular countries or a domestic threat, she said: "Either, overseas and within New Zealand where the funds may have been obtained through non-legal activity."
The problem was worldwide.