The cash-strapped Auckland Council has little interest in a commuter rail service between Hamilton and Auckland.

The Waikato Regional Council today provided a paper on the issue to Auckland councillors, who supported the idea in principle but said it is a low priority, particularly given the growth challenges facing the region.

Mayor Phil Goff said at the weekend the funding shortfall for transport over the next decade has risen from $4 billion to $7b.

Labour MP Sue Moroney and Hamilton deputy mayor Martin Gallagher are among those pushing for a commuter service between the two cities.

"Anyone with a half a brain would know that if you have a city 100km away, [with] two million plus and a greater Hamilton of 200,000-plus, go figure," Gallagher said in March.

At today's Auckland Council planning committee meeting, the Waikato Regional Council presentation identified significant challenges, including constrained network access, no funding sources and that the previous 2011 study into passenger rail was no longer feasible for today's conditions.

With previous work being out of date, the committee agreed to participate in the preparation of a high-level review to identify the key constraints, benefits and options of a passenger rail service between Auckland and Hamilton.

It also recognised that existing issues cannot be resolved without significant capital expenditure.

Auckland councillor Daniel Newman said the idea was ludicrous and unaffordable.

He said it was essential that the Auckland and Waikato regions respectively declare what each can and cannot afford to fund.

"Auckland already faces billion-dollar deficits and we still have not got electrification to Pukekohe; we don't have rail to Huapai and Kumeu; we don't have Penlink and we are still waiting to get the Mill Rd corridor under way.

"I appreciate the visit from the ratepayers from the Waikato. But there is absolutely no commitment from the Waikato to stump up with the multimillion-dollar capital cost, let alone the ongoing operating cost of subsidising commuter rail between Hamilton and Auckland," Newman said