Greenpeace is concerned that an oil company with an exploration licence off Northland may be bribing iwi leaders to bolster support for their controversial drilling plans.

Greenpeace has taken a picture of three executives from Norwegian oil giant Statoil meeting with an Iwi leader at a Wellington cafe.

Campaigner Mike Smith said it goes against the Norwegian government's protocols specifying that consultation must be done through appropriate procedures and representative institutions.

He said it's an effort to win over individual iwi leaders rather than engaging collectively.

"They've got clear instructions from the Norwegian government that they should only deal with institutions and mandated representatives, that's our main concern."

"There's plenty of evidence of corruption and bribery within the oil industry, it's a pretty well established phenomenon around the world."

"We're just concerned that sort of bribery and corruption doesn't creep into our environment in Northland."

MrSmith said issues as serious as deep-sea oil drilling needs to conducted in a transparent way.

He thinks the public should have the right to know the full extent of Statoil's plans.

PRESS RELEASE: @StatoilASA caught breaking own rules to woo iwi http://t.co/3mtguIbLiP #StopStatoil #StopDeepSeaOil pic.twitter.com/KM2suI4EiY

— Greenpeace NZ (@GreenpeaceNZ) August 26, 2015