The head of the National Broadband Network (NBN) wants an industry study to determine the best way to build the high-speed internet project.

Construction has been underway on the NBN for more than two years but there is still debate over which technology should be used.

The NBN Co is using a technology called 'fibre to the premises', which goes all the way to a home, to build most of the network.

But the Coalition wants to use 'fibre to the node'. It says this method is faster and cheaper, but it will come with slower speeds.

NBN boss Mike Quigley is trying to bring an end to the debate in the lead up to the federal election.

He says he supports a proposed study by the Communications Alliance into the pros and cons of a range of technologies to see which is best.

"It gives them an opportunity to have a voice and give their opinion on what is the right way forward for the NBN," he told PM.

"There is a lot of debate at the moment about what the right way forward is. Who's better placed than the industry itself to have a view?"

But he says his support for the study does not mean he does not fully support the NBN.

"Having an open debate can only be a good thing for the country," he said.

'Colossal failure'

Opposition communication spokesman Malcolm Turnbull says the study should have been completed before the Government embarked on the NBN project.

"Mike Quigley's statement today is a colossal admission of failure," he told PM.

"It is admitting that the Government has made a hash of this ... that there needs to be an examination of the different options and ... that should have been done four years ago."

"The question should have been asked: 'we want everyone in Australia to have very fast broadband, what are the options to do so, let's rank them in terms of time of deployment, cost of deployment, service delivery outcomes'.

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"That's what we've been begging the Government to do for four years, but they've embarked on this, they've arrogantly dismissed every request for this and now Mike Quigley himself is saying he'd like to see it done."

Mr Turnbull says if the Coalition wins government, it will examine all aspects of the NBN and decide whether the rollout should continue.

"We will ensure there is produced a comprehensive analysis, totally transparent analysis, of what it will take in terms of dollars and time to complete the network on the plan of the current Government," he said.

"We will then produce a similar analysis which shows the savings in dollars and time by burying it, by making changes, along the lines of the kind that we've proposed, using much more fibre to the node, which is consistent with the experience and practice in most other developed markets.

"We'll also ensure there is done a cost benefit analysis by the Productivity Commission, and we will also conduct a very rigorous inquiry into the whole process relating to the NBN.

"I think Australians need to be told the truth about this project, they need to be told how it could possible have been embarked upon with so little analysis."

'Rational debate'

The board of the Communications Alliance, which represents the telecommunications industry, has not yet decided whether it will go ahead with the study.

But its chief executive, John Stanton, says it is the right time to look at the technologies on offer.

"I guess the point is we're not at a late stage of the rollout of the NBN, we're in the very early stages of a nine year or more rollout," he said.

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"The nexus of the idea here is that technologies develop, things are learnt as you start to roll out a network like this, and it is logical and inevitable that over a multi-year rollout, there will be evolution and improvement of the way that the network is deployed.

"So it could make sense to have industry, which after all designed the original reference architecture for the NBN, continue to look at what could make sense."

Mr Stanton says the debate over high-speed internet needs to be taken out of political hands.

"We need a rational, inclusive debate that sits above politics and simply looks at what might be sensible options in the national interest," he said.

Major telco Optus does not agree that the study by the alliance would be effective.

It has issued a statement saying it would be better for individual companies to contribute to the debate on various broadband technologies rather than a Communications Alliance review.

The ABC asked Telstra for a response to Mr Quigley's plan for a study, but it did not reply.