Amazon's opening the doors to its checkout-free supermarket in the United States.

The Seattle store uses cameras and sensors to track customers and their items, then charges their credit cards when they leave the store.

First Retail managing director Chris Wilkinson said we're likely to see other stores following suit.

But he told Kate Hawkesby it'll be tough to scale up the checkout-free supermarkets.

"There is a defined range of products in the store that Amazon is selling so it's not the wide spectrum of products that we have here in the supermarkets in New Zealand."

LISTEN ABOVE AS CHRIS WILKINSON SPEAKS WITH KATE HAWKESBY