"Mr Rudd has broken his key election commitment to build a fibre to the node broadband network for 98 per cent of the population," said a joint statement by opposition leader Malcolm Turnbull and shadow communications minister Nick Minchin.
"His initial commitment of $4.7 billion has now blown out to a $43 billion exposure for the taxpayer."
The duo also pointed out that the NBN network, originally promised by 2008, is unlikely to be finished by 2018 once the Federal Government's scoping studies are completed.
The opposition accused the Rudd Government of wasting 18 months and $20 million on "a failed tender process that has not delivered a single new broadband service to a home and won't for a long time yet."
The alternative model proposed today by the Government was tantamount to the "building of a new Telstra," the opposition said.
"Mr Rudd is building a second Telstra owned by the Government. With one Telstra having been sold to the public, Labor is now proposing to build a second Telstra to compete with the first."
The Opposition estimates that at $43 billion of cost, the average broadband user would have to pay $200 per month to make new broadband services enabled by the project to be commercially viable.
"No evidence has been provided that there will be sufficient demand for this service at prices that will deliver a commercial return," the opposition said.
The rhetoric stepped up a notch further when Senator Stephen Conroy addressed the opposition's concerns in a statement late this afternoon.
Conroy said the opposition's objections "condemns Australia to a broadband backwater."
"If the Liberal party wins the next election their first act will be to scrap the biggest job supporting infrastructure project in Australian history," Conroy said.
"The Liberal Party and Nick Minchin need to stop living in the past and join the broadband revolution."