Environmental groups have written to Australia’s offshore petroleum watchdog to urge him against speaking alongside the oil lobby at a pro-industry event titled The Great Australian Bight: The Big Opportunity.

The head of the National Offshore Petroleum Safety and Environmental Management Authority (Nopsema), Stuart Smith, is listed as one of three keynote speakers at the South Australian “parliamentary friends of the resource sector” forum dinner on Tuesday.

The event is described as a “deep dive into oil exploration and its economic potential for South Australia”, featuring speeches from Equinor, the Norwegian oil giant currently seeking regulatory approval to drill in the Bight, and the Australian Petroleum Production & Exploration Association, the oil and gas industry body.

An invitation for the event says Nopsema will speak about the history of drilling in the Bight and how “offshore petroleum activity is regulated, to protect the environment and communities”.

Nopsema says its participation is completely neutral, and is being used only to explain its regulatory role and functions. The agency – like many other regulators – regularly provides briefings to government and industry as a way of effectively raising awareness about the nature of its work. Nopsema said it would not, in any way, express a position on the value of resources or their exploitation.

“The presentation Nopsema gives at the event will focus on the regulatory assessment processes we administer, and does not provide any commentary on resource exploitation or governmental views on the value of resources,” a spokesman said. “Nopsema presents at industry-focused events where appropriate, such as the annual APPEA conference, and at these events we focus on regulatory process matters.”

Greenpeace has voiced concerns about the regulator’s appearance at such an event and how it will be perceived, given Equinor is seeking regulatory approval to drill in the Bight.

The Greenpeace Australia Pacific chief executive, David Ritter, wrote to Smith on Thursday to urge him to reconsider.

“Respectfully, in my view it is not appropriate for the chief executive officer of an independent regulator to actively participate in events that are set up to endorse the ‘opportunity’ related to activities that it is the authority’s role to independently regulate,” Ritter wrote.

“In particular, it is improper to participate in a speakers line-up that includes: a proponent actively seeking regulatory approval to drill for oil; the industry body that exists to promote the profitability of the proponent and other firms with a commercial interest in exploration in the Great Australian Bight; and no other stakeholders.”

Equinor is pushing ahead with its plan to drill in the Bight.

Last month, it published a 1,500-page draft environment plan on its website as part of a bid to create more transparency around the project.

Equinor has given the public 30 days to comment through Nopsema.

Nathanielle Pelle, a senior campaigner at Greenpeace, said while it wasn’t unusual for a regulator to give presentations about its role, Nopsema was supposed to be an impartial authority and an appearance at an event specifically promoting oil exploration in the Bight was questionable.

“I’d argue that it is already putting them in a position where they’re no longer impartial,” he said.

“It gives tacit endorsement to the project as a positive before we’ve started to assess the risk.”