Mayor Len Brown said they were consented under rules inherited from the former Auckland Regional Council and council could not legally decline or publicly notify them under those rules. Nor did the council have the power to revoke or reverse the consents, he said.
The legal action follows a public outcry at the port company's plans to extend the wharves and reclaim the seabed between them over time. Mr Brown has refused to say if he supports further port expansion, but is setting up a study on the economic, environmental and social impact of the port on wider Auckland - something he promised in 2013.
Yesterday, Mr Brown walked out of a council meeting following a stoush with councillor Cathy Casey over port expansion, when she accused him of not listening to the people of Auckland.
Urban Auckland, made up of architects, urban designers and planners, has hired Julian Miles, QC, and other lawyers to fight the council and port company.
A letter to council chief executive Stephen Town and ports chief executive Tony Gibson, prepared by lawyer Geoff Hardy, said the council should have publicly notified the wharf extensions.
"We invite council and more particularly POAL (Ports of Auckland Ltd) to take a pause before any construction is undertaken within the Waitemata Harbour," Mr Hardy said in the letter.
"Rather than protect the Waitemata Harbour, council has allowed POAL to take more for itself without any public input. It failed to require an integrated and holistic assessment of POAL's expansion. That was unlawful," Mr Hardy said.
Last night, the council and ports company said they had not seen the letter and could not comment.
Legal moves to stop expansion
• Urban Auckland gives notice of legal action against council and ports.
• Calls for port company to not start construction of two wharf extensions.
• Top QC Julian Miles and other lawyers fighting the case.
• Lawyer says public should have been given a say on wharf extensions.
• Ports and council say they have not been notified.