The Auckland Council has split unexpectedly over how and when to introduce its 30-year growth blueprint.
Nearly half of the 21 councillors have signed a letter siding with the Government on an issue the council says is crucial to the city's development.
The split emerged as council leaders were appearing before a parliamentary select committee on Monday.
The council wants the Unitary Plan in place three years earlier than the Government will allow in order to cater for housing demand.
At the back of the hearing room, councillors led by Christine Fletcher circulated a letter to Prime Minister John Key saying nine disagreed with the council majority.
Ms Fletcher says the three years proposed by the Government for hearings is needed to ensure that the right decisions are made for the future of Auckland.