Seven North Island councils have formed an alliance to collaborate on inter-regional issues such as economic development and transport.
The Upper North Island Strategic Alliance comprises the Northland, Waikato and Bay of Plenty regional councils as well as Auckland, Hamilton and Tauranga city councils and the Whangarei District Council.
The Alliance will represent a combined population of 2.3 million.
Auckland mayor Len Brown says the aim is to increase the contribution made by the top half of the North Island to New Zealand's economy.
He says the alliance has no decision-making authority but can make recommendations to the seven constituent councils and to central government.
At a signing ceremony on Saturday afternoon, at the Auckland Town Hall, representatives agreed to play a key role in the crisis involving the stricken Rena off Tauranga.