Major supermarket chains could be next in line after petrol companies to receive closer scrutiny from the Government after expedited market study legislation becomes law.

Prime Minister Jacinda Ardern said she "would not be surprised" if the Commerce Commission conducted a market study into the supermarket sector.

On Monday, Ardern announced the Government would prioritise the passing of the Commerce Amendment Bill so it would be passed in two weeks.

When law, it will mean the Commission will be able to undertake "market studies," which will compel companies to provide information proving they are behaving competitively.

Ardern said she will personally be nominating the petrol industry to be the first sector to be investigated.

She was asked by Stuff if the supermarket sector could be the next to be looked into.

"Other areas around the cost of living have been raised ... I wouldn't be surprised if we see a nomination in other areas like that."

"Particularly, when New Zealanders compare what happens in Australia, Kiwis say, 'Why are we seeing that marked increase here?'"

New Zealand's supermarket sector is largely made up of Foodstuffs, which owns New World and Pak'n'Save, and Woolworths, which owns Countdown.

According to the legislation, an MP would have to nominate the supermarket sector to be investigated by the Commerce Commission.

A spokesman for the Prime Minister told the Herald that other areas around the cost of living had been raised, and she wouldn't be surprised if there were nominations in other areas or industries.

"At this stage, the Government has no plans for market studies until the Bill is passed and we have been clear the first industry to be looked at is the fuel industry. There is no commitment to look at the supermarket sector at this time."