The authorities made more than 500,000 requests for confidential communications data last year, equivalent to spying on one in every 78 adults, leading to claims that Britain had “sleepwalked into a surveillance society”.
An official report also disclosed that hundreds of errors had been made in these “interception” operations, with the wrong phone numbers or emails being monitored.
The figures will fuel concerns over the use of the Regulation of Investigatory Powers Act by public bodies.
The Act gives authorities – including councils, the police and intelligence agencies – the power to request access to confidential communications data, including lists of telephone numbers dialled and email addresses to which messages have been sent.
Councils have been accused of using the powers, which were originally intended to tackle terrorism and organised crime, for trivial matters such as littering and dog fouling. Only last month, it emerged that councils and other official bodies had used hidden tracking devices to spy on members of the public.
The latest figures were compiled by Sir Paul Kennedy, the interception of communications commissioner, who reviews requests made under the Act. They relate to monitoring communication “traffic” – such as who is contacting whom, when and where and which websites are visited, but not the content of conversations or messages themselves.
Sir Paul found that last year a total of 504,073 such requests were made. The vast majority were made by the police and security services but 123 local councils made a total of 1,553 requests for communications data. Some councils sought lists of the telephone numbers that people had dialled.
Amid growing unease about surveillance powers, ministers issued new guidelines last year about their use. Despite the promised crackdown, the 2008 figure is only slightly lower than 2007’s 519,260 requests.
In April, the Home Office said it would go ahead with plans to track every phone call, email, text message and website visit made by the public, in order to combat terrorists and other criminals.
Chris Huhne, Liberal Democrat home affairs spokesman, said: “It cannot be a justified response to the problems we face in this country that the state is spying on half a million people a year.
“We have sleepwalked into a surveillance state but without adequate safeguards.”
Sir Paul found 595 errors in interception requests last year, including mistakes by MI5 and MI6, the intelligence agencies.
However, he defended councils over their use of the Act, concluding: “It is evident that good use is being made of communications data to investigate the types of offences that cause harm to the public.”
His report even encourages councils to acquire more communications data, saying that “local authorities could often make more use of this powerful tool to investigate crimes”.
A Home Office spokesman said: “It’s vital that we strike the right balance between individual privacy and collective security and that is why the Home Office is clear these powers should only be used when they are proportionate.”
