West Yorkshire Police are snooping on phone calls and e-mails an average 35 times a day, it has been revealed.
Surveillance watchdog Sir Anthony May has said police tap into communications data far too frequently and warned that privacy might be at risk.
And he announced an inquiry into whether there should be stricter curbs.
West Yorkshire is among the forces using the powers the most, a report to Parliament reveals – a total of 12,676 timess in 2013.
That works out at 1,056 every month across the district – or 244 times every week.
Authorisation is granted to uncover the “who, when and where” of a communication, such as who owns the phone or e-mail address or computer IP address.
The police also learn with whom that person was in contact electronically – but not what was said in the communication.
Sir Anthony, the Interception of Communications Commissioner, said public bodies had secured a total of 514,608 requests for communications data last year.
His report concluded: “It seems to me to be a very large number. It has the feel of being too many.
“I have accordingly asked our inspectors to take a critical look at the constituents of this bulk to see if there might be a significant institutional over-use.
“This may apply in particular to police forces and law-enforcement agencies who between them account for approaching 90 per cent of the bulk.”
Nationwide, most communications were tapped into to “prevent or detect crime or prevent disorder”, followed by “emergency to prevent death or injury”. West Yorkshire Police was asked to comment on the scale of its use of the powers and in what circumstances they were used but declined to do so.
Instead, the Telegraph & Argus was directed to a statement from the Association of Chief Police Officers that said police would “await the findings of the inquiry”.
It added: “We remain convinced that there is a significant role for communications interception and the acquisition of data communications in keeping the public safe.
“Our commitment to balancing that with our legal and human-rights duties remains equally strong.”
Home Secretary Theresa May backed forces, saying: “Communications data is vital in helping to keep the public safe. It is used to investigate crimes, bring offenders to justice and save lives.”
The annual report also highlighted many local authorities that snooped on phone calls and e-mails last year – but none in West Yorkshire did so.