UPDATED 9.11am More international retailers could be coming to our shores.

LISTEN ABOVE: Jonathan Elms, associate professor of retail management, spoke to Rachel Smalley

H&M opens its first New Zealand store at Auckland's Sylvia Park tomorrow, followed by Spanish retailer Zara next week.

Associate Professor in retail management at Massey University Jonathon Elm told Rachel Smalley it'll be a challenge for our retailers.

New Zealand retailers will have to up their game, particularly in terms of the in-store experience and fast fashion, he said.

Associate Professor Elm said the likes of Topshop, which has been open here for more than a year now, have been doing incredibly well.

He wouldn't be surprised if other international retailers decide to head our way.

Although, shoppers are being told big retailers aren't always as sustainable as they make out to be.

Sustainable fashion expert for the Guardian Lucy Siegle told Larry Williams H&M claims to recycle the fibres in its clothing, but that's actually very hard to do.

"They can only recycle a tiny tiny amount so I think it's a little bit overcooked some of the sustainability initiatives that some of the fast fashion brands have brought into play."

Siegle said big retailers like H&M are now producing more clothes quicker than ever.

Creating clothes at such a pace, and selling them so cheaply, means workers are incredibly disadvantaged, she said.