The prime minister hinted that the scheme would cost up to $400m when he visited the Gold Coast on Wednesday to campaign on the importance of storing telecommunications data to investigate child exploitation crimes.
“There are a range of figures … but even at the highest estimate it’s less than 1% of this $40bn a year and growing [telecommunications] sector,” Abbott said.
The government has pledged to contribute to the industry’s costs of adjusting to the new storage requirements, but it remains unclear how much will be borne by taxpayers.
Guardian Australia asked the attorney general’s department direct questions about the total estimated cost, the share that taxpayers would contribute and the technical details known as the “dataset” governing what would be captured.
But the department could not shed light on specifics of the scheme that would require telcos and internet service providers (ISPs) to store customers’ phone and email records for two years.
In response, the department said the government had “consulted extensively with industry and engaged PricewaterhouseCoopers to cost the data retention scheme” and had briefed the parliamentary joint committee on intelligence and security.
It said the government would await the committee’s recommendations – due on 27 February – “before commenting further”.
Abbott visited the Gold Coast headquarters of the child-protection organisation Bravehearts on Wednesday to broaden his pitch for public and political support for the scheme beyond investigating terrorism suspects.
“It’s very important if we are to protect our kids that the police have access to appropriate telecommunications data,” he said.
“We all know that people who want to abuse children often feed their habits online. It’s very important that we have the information that allows this kind of horrible crime, this kind of horrible behaviour, to be tracked and prosecuted.”
Abbott said “an explosion in unsolved crime” would be the consequence of police losing access to data that telecommunications companies were increasingly not storing for their own business purposes.
“If we want to combat crime, we need this legislation and, if we don’t get it, it will be a form of unilateral disarmament in the face of criminals and the price of that is very, very high indeed,” he said.
A spokesman for the Liberal Democratic party senator David Leyonhjelm said a $400m total cost equated to slugging every Australian $20 “for the privilege of having the government snoop on us”.
The Greens senator Scott Ludlam said it was a proposal “with open-ended costs and unknown consequences, fast-tracked to distract away from the prime minister’s terminal leadership”.
“Tony Abbott wants the parliament to write a blank cheque for mass surveillance,” Ludlam said.
The opposition leader, Bill Shorten, said the Labor and Liberal parties were united on the goal of fighting terrorism, but parliament had an obligation not to rush legislative proposals and to consider any unintended consequences.
Labor MP Ed Husic said the opposition would wait to see what the security committee recommended next week, but he personally had held concerns about the proposal “for quite some time”, including the potential impact on smaller telcos.
“You’ve heard concerns expressed about creating a pool of data that could be hacked into and that would not necessarily be as secure as possible,” he told Sky News.
“I think there are broader community concerns ... that are being levelled at both government and business about the amount of data that they collect and the way that they retain and use that data, and you’ve also seen on the international scale that there has been pushback from big companies like Google and Facebook and others about the way in which the US government has been accessing data.”
John Stanton, chief executive of the Communications Alliance representing industry, said the scheme would require service providers to change their IT systems.
Stanton said the government was yet to clarify what contribution it planned to make to these costs, which would have a bearing on how much would have to be passed on to consumers through their bills.
He said the fact popular web-based email providers such as Gmail would not be captured by the scheme raised concerns that local ISPs were being placed at a competitive disadvantage.
Stanton warned against parliament rushing to pass the legislation. “We think parliament should never be rushed,” he said. “It should have a good opportunity to scrutinise legislation and consider it.”
In the past fortnight, Abbott has stepped up his calls for parliament to pass the bill “as quickly as we can” including holding a joint press conference alongside the Australian federal police commissioner, Andrew Colvin, in Melbourne.
On 5 February, Abbott said the scheme would give the public the protection they had a right to expect “in the wake of the attack on the policemen here in Victoria, in the wake of the Martin Place siege, in the wake of the Charlie Hebdo atrocity”.
Last week, after reading to parliament alleged evidence against two men facing terrorism charges, Abbott said the legislation “must be passed if our community is to be as safe as it should be in these difficult times”.
In a YouTube message posted on Sunday, Abbott flagged a new round of national-security laws while declaring that the data retention scheme would “make it easier to keep you safe”.