Conservationists have launched a legal challenge against plans to drill for oil in the Great Australian Bight.

The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) is being taken to court by The Wilderness Society over its approval for Norwegian oil company Equinor to conduct drilling.

It is alleged that Equinor did not consult “important and relevant parties” as required by regulations.

Equinor - majority owned by the Norwegian Government – wants to drill the ‘Stromlo-1’ exploration well 372 kilometres south of the Nullarbor coastline, off South Australia.

NOPSEMA’s conditional environmental approval allows the company to drill 24 hours a day for about 60 days.

The environmental approval process took eight months, including reviews of over 30,000 submissions. Equinor was twice required to modify and resubmit its plans.

The current plan is to to use a mobile offshore drilling unit, supported by three ships and two helicopters.

But environmental groups oppose drilling in the Bight because of the threat of a catastrophic oil spill.

The Wilderness Society is a member of the Great Australian Bight Alliance, which also includes the Mirning Indigenous people, whose traditional lands cover far south-eastern Western Australia.

The society claims that Equinor refused to formally consult with it or other environment groups, as well as “key Indigenous groups and local governments”.

“The precedent that has been set by NOPSEMA's approval of Equinor's environment plan means that in the future, environment groups, traditional owner groups, local governments, aren't relevant people for proposals like this to be involved in consultation,” Wilderness Society SA director Peter Owen said outside court.

“That is a precedent that cannot be allowed to be set in this country.”

Neither Equinor nor NOPSEMA have spoken publicly about the ongoing court case.

NOPSEMA rejected Equinor's draft plans last June, saying the company needed to explain why it did not consider the Wilderness Society, Sea Shepherd Australia, the Mirning and Ngarrindjeri people or Adventure Bay Charters as parties to be consulted.

Equinor says it met with Barngarla, Narungga, Nauo and Wirangu people during consultation, but that “the Mirning and Ngarrindjeri peoples did not claim they were relevant persons during the public comment process”.

NOPSEMA rejected this assertion.

“This is not considered a sufficient reason to determine that the Mirning and Ngarrindjeri people are not relevant persons, and is incorrect in the case of the Ngarrindjeri people,” NOPSEMA said in November, before environmental approval was granted in December.

“It is also noted that the Mirning people have repeatedly and publicly expressed their desire to be consulted.”