The expansion in official snooping on communications records has continued with a record number of requests last year for details of who is talking to whom.
In the 12 months to 31 December, authorities made 525,130 requests to phone companies and inernet providers for communications data, the Interception Commissioner Sir Paul Kennedy revealed in his annual report.
The figure is up on 504,073 requests in 2008, and beats the previous record of 519,260 requests in 2007.
Sir Paul said the increase was due to more demand from police forces.
"I cannot give a precise reason for this but there is evidence that more and more police forces have to investigate Internet related crime, including paedophile rings and the requirements to obtain communications data in these types of cases can be quite extensive," he said.
"In other words one police investigation can generate a large number of requests for data."
The relevant data describes the who, the how, the when and the where of communications, and authorities do not require external approval to access it. The interception of the content of communications is legally separated and requires a warrant from the Home Secretary or Scottish government.
Communications data is meanwhile available to dozens of public authorities, including local councils. The government has announced a review to remove some surveillance powers from local authorities..
A total of 661 errors were reported to Sir Paul last year, with public authorities responsible for about three quarters, and communications providers the rest.
"I am not convinced that any useful purpose would be served by providing a more detailed report of these errors," the Commissioner's report says. It includes the same line every year, while assuring that none were due to "wilful or reckless" misconduct.
Offical use of communications data seems set to increase despite the coalition's pledge to to end the storage of phone and internet records "without good reason". Home Offical officials running the Interception Modernisation Programme are trying to square that political statement with demands from the intelligence services for communications providers to be compelled to retain much more data from the internet. ®