Police are using counter-terrorism laws to confiscate mobile phones from any passenger travelling through the UK's international borders by air, rail or sea, and then download their data.
The blanket powers allow officers to carry out indiscriminate seizures without showing any reasonable suspicion. The downloaded information can be retained for "as long as necessary."
Data collected includes contact lists, call history, photos and details of who a person has been emailing or texting, but not the content of the messages.
Details of the practice were first revealed late last week by David Anderson QC, the independent reviewer of terrorism laws, through a post titled "One law for the street, one for the arrivals hall?" on his dedicated website.
"Schedule 7 empowers police officers to stop, examine and search passengers at ports, airports and international rail terminals, compel them to answer questions aimed at determining whether they are terrorists, and detain them for up to nine hours and their possessions for up to a week.
"Data from mobile phones and laptops may be downloaded and retained by the police for substantially longer periods than that," he wrote.
Expanding on the powers the law gives, Anderson told The Telegraph, "Information downloaded from mobile phones seized at ports has been very useful in disrupting terrorists and bringing them to justice.
"But ordinary travellers need to know that their private information will not be taken without good reason, or retained by the police for any longer than is necessary."
Anderson is expected to raise concerns about the actions in his annual report on terrorism laws due to be published this week.
Up to 60,000 people a year are examined for periods of over 15 minutes under the 2000 Terrorism Act. It is not known how many have had their data downloaded.
Dr Gus Hosein of the campaign group Privacy International said, "Seizing and downloading your phone data is the modern equivalent of searching your home and office, searching through family albums and business records alike, and identifying all your friends and family, then keeping this information for years.
"Under law, seizing a mobile phone should be only when the phone is essential to an investigation, and then even certain rules should apply. Without these rules, everyone should be worried."
Image credit: Flickr (James Cridland)