Energy Minister Judith Collins says an inquiry into fuel prices will be an "in-depth'' probe into whether New Zealanders are paying a fair price at the pump.

Collins has released the terms of reference for the inquiry into the financial performance of the fuel market, which was prompted by concerns that fuel margins - the cost difference in what fuel is imported and sold for - were increasing.

It will rely on fuel companies providing their financial information to the inquiry team, which Collins said was necessary to allow a swift initial analysis of whether there was a problem.

Collins said it would help the Government understand if there was an issue in the way fuel margins had steadily increased over recent years and, if so, how to address it. While it would be a technical inquiry, she expected "observations" about regional price differences.


"We need to know what is happening and determine if what people are paying at the pump is reasonable or whether companies are making super-normal profits."

​The terms of reference note that MBie had observed a trend of rising importer price margins since 2008 and would assess whether that was warranted and significant or not.

The inquiry team would look at the annual margins of each of the main businesses - Z Energy, BP, Mobil and Gull - and the returns on capital for the fuel companies at different stages of the supply chain.

That would be compared with other countries.

The companies will be asked to provide information broken down by markets - such as aviation, marine and retail - and different fuel types, as well as by regions. The review would also consider what future trends could be expected.

It says the study may also look at the effectiveness of competition and how to improve it in the relevant markets.

The inquiry is expected to be completed by June and will be done by consultants appointed by MBie.