A proposed oil exploration permit on Auckland's west coast overlaps with the habitat of the critically endangered Maui's dolphin.

Auckland Council is set to lend its might to the campaign to save the Maui's dolphin.

Councillors are likely to vote today to oppose an oil exploration permit on Auckland's west coast which overlaps with the habitat of the critically endangered dolphin.

Environmental group Greenpeace is planning a demonstration outside the Town Hall this morning in support of the vote.

Oil exploration within a sanctuary set up to protect Maui's dolphins could lead to further loss of the animals, council chief planning officer Roger Blakeley said.

"So it seems to us to be a critically important issue from an environmental and biodiversity concern."

The West Coast Marine Mammal Sanctuary was set up in 2008 and runs from Northland to Taranaki, including Auckland's west coast. It extends 12 nautical miles out to sea.

The areas the government are offering up for deep sea exploration, known as Block Offer 2015, go within six nautical miles of the shore and therefore impinge on the sanctuary.

Last year it approved exploration in a similar area. Auckland Council argued then that the edge of the permitted blocks should be moved out to 12 nautical miles from the coast to avoid any impact on the dolphins.

The government rejected its submission, saying existing protections were adequate.

Now council officials have recommended that it put in the same submission again this year on Block Offer 2015.

Councillors will vote whether to go ahead with the submission at their Regional Strategy and Policy Committee meeting this morning.

The council did not want much, as the total area of the block in question this year was 61,000 square metres and the overlap with the sanctuary was just 125 square metres, Blakeley said.

"We think it's a very small thing to ask, but a very important thing to ask."

The council has until February 9 to have it say on the proposed exploration permits.