Greenpeace has requested an urgent hearing at the Wellington High Court into its application for a judicial review of a decision allowing exploratory drilling for oil in deep sea off the Raglan coast.
The Texan oil company Anadarko's ship, the Noble Bob Douglas, began drilling at 2.30am on Tuesday, not long before a flotilla of protest boats returned to port.
Greenpeace believes that New Zealand's Environmental Protection Authority made an error in law by allowing Anadarko to go ahead without looking at key documents.
Lawyer Duncan Curry said Greenpeace believes the EPA's assessment to be lacking in a number of areas, including contingency plans in the case of an emergency spill, and that Anadarko has not complied with legislation.
Anadarko corporate affairs manager Alan Seay said the Noble Bob Douglas would drill for 70 days, when it is expected to reach its target depth.
The Green Party's energy spokesperson, Gareth Hughes described the process around granting Anadarko permission to drill as an utter shambles, and said the company should stop work as Greenpeace pushes its case.
However, Prime Minister John Key said the EPA is confident it made the right decision.