The cost of collecting and retaining the internet connection records (ICRs) of every UK citizen would be £1bn, enough to employ 3,000 full-time police officers, according to a report by the Don't Spy on Us coalition.
The group, which includes the Open Rights Group and Privacy International, arrived at this figure based on a similar plans mooted in Denmark but subsequently dropped after costs of £105m a year were arrived at by Ernst & Young.
The UK has a population seven times that of Denmark, and Don't Spy on Us believes that the costs will easily spiral to £1bn just to set up the necessary infrastructure to collect and store the data.
Lord Paddick, Liberal Democrat spokesman on home affairs in the House of Lords and former deputy assistant commissioner at New Scotland Yard, insisted that the government's plans are unworkable.
"This highly controversial plan to record everything that all of us do on the internet was already facing serious problems," he said.
"It is unclear that it is even possible, given the quantity of data involved, or how much use it would really be to the police. Sensitive personal information that could reveal everything about our lives would be vulnerable to theft by hackers, thieves, blackmailers and hostile foreign governments.
"Now that we have a professional estimate that it would cost well over £1bn in set-up costs alone, and could be easily circumvented by criminals for just a few pounds a week, apart from anything else this represents appallingly bad value for money."
Eric King, director of Don't Spy on Us, said the figure should make the government realise that the costs are becoming unfeasible.
"The government is trying to force ISPs to collect all of our ICRs but refuses to listen when they express concerns about the cost and feasibility of the proposals," he said.
"As in Denmark, the government should commission an independent cost analysis to clarify the true cost of collecting ICRs. There is no evidence that collecting ICRs makes us safer."
Despite numerous criticisms of the Investigatory Powers Bill, including from MPs, the government has shown no signs of backing down, claiming that it is necessary to fight terrorism.
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