Opposition spokesman for communications, Nick Minchin, wrote to the Auditor General in April raising the concerns he had with the termination of the tender process to build a $4.7 billion national broadband network for fibre-to-the-node technology to reach 98 per cent of the population.

Following a preliminary inquiry, Senator Minchin says he's been advised the National Audit Office will now carry out a more extensive performance audit.

Senator Minchin said the Government "wasted" almost 18 months and close to $20m on the process "which at the outset had little prospect of producing a positive outcome".

"Tenderers also spent millions of dollars on their submissions to a fatally-flawed process," he said.

"The bidders themselves confirmed that these objectives were totally unrealistic and unaffordable.

"The process was terminated when it was concluded none of the national bids received offered value for money."

The audit will begin in late June 2009 and be completed in early 2010.