LISTEN ABOVE: Employment Lawyer Hamish Kynaston talks to Rachel Smalley about the legalities around the firing of a Barfoot & Thompson staff member over leaked sales data.

The Barfoot and Thompson data leak has its customers worried.

The real estate agency has fired a staff member who leaked sales information to a number of journalists and politicians.

Labour used it to highlight the disproportionate amount of residential sales to people with Chinese surnames.

Barfoot and Thompson CEO Wendy Alexander admits a number of clients and customers have contacted them about the leak this week.

"To say that they are disenchanted and concerned, that their data could be compromised and it goes from just the weekly sales to sort of what else might be shared."

Wendy Alexander says they have found no evidence of any other information being leaked.

The realty company also reports there's nothing unusual or scary about interest in Auckland homes from Chinese buyers.

Alexander points out Auckland is one of the most culturally-diverse cities in the world.

"It's inevitable that a significant level of our inquiry with regard to list and sell is going to come from Chinese purchasers. There is nothing unusual, unique or scary about that. We welcome their business."

Wendy Alexander says many of the people from Barfoot and Thompson are from those countries too, and are doing a great job, with their results speaking for themselves.

However, Labour MP Phil Twyford hit out at the agency for sacking the staff member who leaked sales data, calling them a "whistleblower." 

“This data provided an important snapshot of what’s going on in the Auckland housing market,” Phil Twyford said.