A hard, no-deal Brexit could be damaging for New Zealand business, Prime Minister Jacinda Ardern has acknowledged.

Speaking to reporters in London ahead of a meeting with British Prime Minister Theresa May, Ardern agreed that if Britain left the European Union on March 29, which would see it exit with no deal in place, it could "absolutely" be damaging for New Zealand business.

"My job is to highlight and focus on the best interests of New Zealand business ... and there's no question that a no-deal situation would be very damaging and very difficult."

The Government's focus was on supporting business if that scenario eventuated.

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"I'm using this opportunity, today and tomorrow, to talk to businesses about some of those preparations, but also planning for every scenario that may arise."

Ardern, who will meet May just before the latter goes back to the House of Commons to outline how she plans to go forward after her Brexit plan was soundly defeated last week, said it was a measure of New Zealand's relationship with Britain that they were meeting then.

"This is still an opportunity for us to continue to reiterate the strength of New Zealand's relationship and our aspiration that once the UK is in a post-Brexit environment, that we will be in a position to negotiate a free trade agreement," Ardern said.

Ardern, who is in London for a day before travelling to Davos, Switzerland, for the World Economic Forum then Brussels for talks with top EU officials, earlier spent time at the Allpress roastery and cafe in Dalston with chief executive Tony Papas and UK Trade Commissioner Nick Swallow.