A group campaigning for a new Auckland harbour bridge has welcomed the Government acknowledging the need for a second crossing, but says more ambition is needed.

The National Infrastructure Plan (NIP) released in Auckland yesterday singled out Auckland as having the largest urban infrastructure "aspirations".

These included the Waterview Connection in west Auckland, the new Waitemata Harbour crossing, a CBD rail tunnel and an airport rail link.

"It is clear that it will not be feasible for Auckland or New Zealand to fund all these multibillion dollar projects at the same time," the report said.

The report said a second Auckland harbour crossing could be needed in 10 to 20 years. There was also a need to replace some of the rail fleet to boost growth on "some routes", with demand for further investment in Auckland and Wellington.

The Anzac Centenary Bridge Group is pushing for a new iconic bridge to start being built by 2015.

Group chairman Richard Simpson said the Government's inclusion of the crossing in the plan was welcome, but it was disappointing that it was earmarked for construction not to start for 10 years as it would be a costly mistake.

Finance Minister Bill English said the plan was a step towards better management of $6b of investment a year and $110b in asset holdings.

The plan was a snapshot of public and private infrastructure, planned investment and the Government's priorities.

Business NZ chief executive Phil O'Reilly said if the Government wanted to succeed it would have to find ways to unlock private capital.

"It is helpful to have a sense of the priority rankings (broadband, electricity, roads, infrastructure for the Rugby World Cup) and to know that more work on the electricity market and agricultural irrigation are emerging priorities. But unlocking private sector involvement requires a commitment to address the problems within a clear, long-lived, strategic framework," Mr O'Reilly said.

"Fundamental to any infrastructure plan is the extent to which it unlocks private sector capital, either in the delivery of infrastructure or in capital that will leverage off infrastructure spend. However, it's hard to see what role the NIP in its current form will play in contributing to these objectives. It's good to have a plan. At this stage it's a work in progress and Business NZ and its members are looking forward to working with the Government to build on it."