The Home Office has said ministers have not yet decided how to retain data on all communication — but has defended the importance of doing so.
Several press reports have said the government will build a single database to hold everyone's communications data, collected from all service providers — adding that this would cost £12bn. These added that GCHQ, the government's surveillance body, has been granted £1bn to build a pilot of this database under the Interception Modernisation Programme.
Communications data does not include the contents of a call, email or webpage, but can often be as revealing. For telephony, it includes numbers called, the name and address of the caller and the IMEI number and approximate location of a mobile phone, while for internet services it includes IP addresses, service and, if appropriate, telephone line used.
The Home Office said the means are still under consideration, but that the aim of collecting all communications data is justified, calling it "a vital investigative and evidential tool" for law enforcement. It is also required of the UK under a European directive, and a bill is expected in the Queen's speech.
"At the moment, the police can get critical information from communications service providers such as telephone companies to help them solve crimes," said a spokesperson. "This information is used in order to prevent and detect crime on a day-to-day basis — including serious crimes and terrorism.
"However, developments in technology mean that this capacity needs to be updated. Ministers and officials are considering how best to do this and what legislation is needed to ensure adequate safeguards are put in place to protect the privacy of the public."
Privacy advocates argue that a single database would allow trawling and profiling of the entire population, while leaving the data with service providers would ensure it would only be retrieved for those who are under suspicion.
A Home Office consultation document on implementing the directive recommends minimising the duplicated storage of data — such as by excusing a reseller of services from holding data if it is kept by the actual provider — while ensuring that all kinds of this data are collected by insisting that internet communications data is retained.
It says such an approach would cost £30.4m in capital costs and £16.2m over eight years in running costs.
