Under the Resource Management Act, the council regulates and assesses the environmental effects of any mining activity.
In a report considered by councillors yesterday, officers said there was a significant potential for economic benefits for Auckland if oil or gas production wells were developed off the city's coast.
"Oil and gas exploration has environmental risks that are of low likelihood but high consequence. In Auckland this relates principally to Maui's dolphins and to drilling well blowouts."
Endangered Maui's dolphins are found off Auckland's west coast adjacent to the block areas. Officers said extending the oil exploration boundaries to 12 nautical miles would protect their environment.
Read more on the submission approved by the council here.