NBN is value for money, minister says

NBN Co says construction costs will be around 3.9 per cent higher than initially forecast. (AAP)

NBN Co says construction costs will be around 3.9 per cent higher than initially forecast. (AAP)

The national broadband network will deliver value for money, despite higher building costs and completion delays, the federal government says.

Labor's national broadband network (NBN) will deliver returns to taxpayers, despite a rise in construction costs and delay in the finish date of the $37 billion project, the federal government says.

Communications minister Stephen Conroy and network builder NBN Co Ltd released an updated three-year corporate plan for the project on Wednesday, setting out new financial parameters until it's completed in 2021.

Construction costs over the life of the biggest public infrastructure project in Australia's history are forecast to rise by almost four per cent to $37.4 billion, and its finish has been pushed out by six months.

But NBN Co remains on track to meet its target to pass 758,000 premises by the end of 2012 and lift the total premises on the high speed network rollout to 3.5 million by mid-2015.

Senator Conroy said the plan, which updates an earlier program released in December 2010, showed the government was delivering on its promise to give all Australians access to a reliable and affordable service.

"The NBN is a sound investment that will pay its own way and generate a seven per cent return to the taxpayer," he told reporters in Sydney.

NBN Co chief Mike Quigley said while construction costs had risen, this was due to the impact of major commercial deals and regulatory delays beyond its control.

Now those issues were settled, the project's plan was on a more solid footing.

"It is a much more fact-based, solid set of assumptions ... than it was back in December 2010," Mr Quigley told AAP.

But opposition communications spokesman Malcolm Turnbull said the government had let down taxpayers.

"Labor's national broadband network is falling disastrously behind every benchmark the government has set for it except one - the amount of taxpayers' money being spent," he said.

He said NBN Co should be given a definite budget and stick to it, and repeated his call for the Productivity Commission to conduct a thorough cost-benefit analysis of the project.

The opposition has consistently focused on the fact that there's no independent cost-benefit analysis of the project, while arguing the private sector could deliver something similar without putting more than $30 billion of taxpayers' money on the line.

Mr Quigley repeated NBN Co's commitment to delivering lower prices for wholesale fixed-line broadband access, as more consumers migrated to the network.

"What is especially good news, we expect usage and speed profiles to go up, which means we may be able to bring wholesale prices down faster than we otherwise would," he said.

Independent MP Rob Oakeshott, who chairs federal parliament's NBN committee, said the NBN was a sensible public policy.

"It'll cost more but ultimately it will return more to the taxpayer," he said in a statement.

NBN Co aims to deliver fibre-optic cable broadband to 93 per cent of Australia homes, schools and businesses by June 2021.

Of the remainder, four per cent should receive broadband services through wireless networks and three per cent through satellite services by 2015.