Image copyright Getty Images Image caption Whatever you call them, the beloved snack food is made with "crisping varieties" of potato

New Zealand is facing a potential crisps shortage this summer, producers say, in a snack crisis being labelled the "chipocalypse".

Persistent wet winter weather on the islands has hit potato production, resulting in higher prices.

In some places, up to a third of the crop has been lost.

And crisps - which are made with a particular kind of potato from affected regions - have been hit particularly badly.

Industry body Potatoes New Zealand says the price for a kilogram of potatoes has already risen sharply in the past year from AUD $1.63 in August 2016 to $2.12 a year later.

But the ongoing trouble in potato farming did not capture mainstream attention until a warning appeared on some supermarket crisp aisles.

Seasons are inverted in the northern and southern hemispheres - so it is now spring in Australasia, following a particularly bad winter.

"It started raining in March, and it just simply hasn't stopped," said Chris Claridge, head of Potatoes New Zealand, blaming the third-wettest year on record.

Speaking to Radio Live NZ, he said farmers had not had the dry periods their crops needed.

"Potatoes are actually alive - they need to breathe. And so effectively they drown, and then they start to rot... because they're submerged in water," he said.

Waterlogged fields also make it difficult for farmers to get to their fields and save the crop, he said - because the soil cannot support the weight of a tractor.

New Zealand's North Island, where crisping varieties are grown, has suffered most, he said - but fresh potato supply from the South Island is largely unaffected.

It would take some months for the shortage to hit shelves - and it is likely to hit processed potato foods more than fresh stocks.

"You will have new potatoes for Christmas, I promise you that," Mr Claridge said.

Supermarket chain Pak n' Save, whose warning signs prompted national headlines, later downplayed any potential shortage, claiming it "was actually due to an ordering error" - prompting some social media users to wonder if the "chipocalypse" was just a myth.

But a company spokeswoman did tell stuff.co.nz that growers were "highlighting a potential future potato shortage".

The two largest supermarket chains both told the new site they were "working with suppliers" to avoid any problems.