Monitoring plans will cost £1.8bn

Controversial moves to give police, security services and tax officials access to details of people's phone calls, emails and internet usage will cost the taxpayer at least £1.8 billion, it has emerged.

The price tag for what critics call the "Snooper's Charter" was disclosed as Home Secretary Theresa May published draft legislation for the plans.

The 10-year bill includes the costs of equipping internet and telephone companies to retain and store data on behalf of the police, the security services, the Serious Organised and Crime Agency and HM Revenue and Customs.

It also covers reimbursing communication service providers for processing requests for data. The Home Office said the expected benefits from the outlay would be in the region of £5 billion to £6.2 billion, which will include the gains from reducing tax fraud and seizing criminal assets.

Mrs May also compared the average £180 million-a-year cost of the plans with the annual policing bill of £14 billion. She said: "This communications data is vital for catching criminals. If we don't do this, if that money isn't spent, then we are going to catch fewer criminals."

Amid criticism from civil liberties campaigners that the Communications Bill heralds an unwarranted intrusion into people's privacy, she insisted the innocent had nothing to fear. "The only people who have anything to fear from this are the criminals," she said.

The Home Secretary said the draft Bill would not introduce real-time monitoring or allow the content of communications to be subject to surveillance. Local authorities would not have access to the information, said Mrs May.

Despite disquiet among Liberal Democrats about the proposals, Mrs May said Deputy Prime Minister Nick Clegg was signed up to the Bill. But Conservative backbencher David Davis said PM David Cameron had attacked similar proposals when they were advanced by the former Labour government in 2009.

"It's not content, but it's incredibly intrusive," he said. "If they really want to do things like this - and we all accept they use data to catch criminals - get a warrant. Get a judge to sign a warrant - not the guy at the next desk, not somebody else in the same organisation."

Nick Pickles, director of privacy campaign group Big Brother Watch, said the Bill was "an unprecedented and unwarranted attack on our privacy that will see the Government track where we make calls, who we email and what everyone does online".