Skyrocketing fuel prices across New Zealand have created a black market in which petrol is exchanged for methamphetamine.

Petrol prices hit a 30-year high in September and there's no sign they'll be slowing down any time soon. New Zealand has the highest pre-tax fuel cost in the OECD, with prices rising by a massive 39 cents between October 2017 and September 2018.

In the last decade, fuel importers doubled their margins they take for themselves, significantly driving up how much Kiwis pay at the pump.

Two weeks ago Prime Minister Jacinda Ardern said motorists were being fleeced and promised to force through a new Bill which would force the fuel industry into greater transparency.

Meth users have spied an opportunity, fleeing from petrol stations with tanks full of stolen fuel which is then exchanged for hundreds of dollars' worth of meth.

Porirua man Christopher Ashley Tyacke was recently sentenced to nine months of home detention after stealing petrol from stations all around the Wellington region, according to Stuff.

Wellington and the South Island have seen particularly high petrol price increases.

Tyacke told Stuff that 300 litres of petrol could buy about a gram of meth, valued at approximately $450 on the black market.

The 34-year-old, who was once a daily meth user, said it was a "big industry" in New Zealand, "almost like a pre-order thing".

He said he didn't feel as bad about stealing petrol compared to other kinds of theft because he was taking money from big international companies.

"It was an easy way to get it without screwing people over, without ripping off families," he told Stuff.

Employees at Z and BP don't have to pay for petrol stolen on their watch.

Z confirmed the chain had seen more "drive-offs" in the last month than usual, Stuff reports.

Newshub.