The UK government is planning a huge database that would hold details of all phone calls, text messages, emails and internet use of every UK citizen.
The database is being touted as a way to combat terrorism and will be introduced in a new Communications Data Bill planned for the Queen's Speech in November.
Information would be held for 12 months and could be accessed by police and security services in possession of a court order.
"We have warned before that we are sleepwalking into a surveillance society, " said assistant Information Commissioner Jonathan Bamford.
"Holding large collections of data is always risky. The more data that is collected and stored, the bigger the problem when the data is lost, traded or stolen.
"Defeating crime and terrorism is of the utmost importance, but we are not aware of any pressing need to justify the government holding this sort of data. "
Technology companies have been quick to challenge the move, pointing out that such a vast database would be immensely difficult to manage, would be a boon to identity thieves and would do little to counter terrorism.
Jamie Cowper, a data protection and encryption expert at PGP Corporation, said: "You have to admire the government's gall in attempting to bring in yet another 'super-database' with public confidence still in tatters over recent data lapses.
"Surely it would be more logical to focus on fixing the existing databases and proving their security before introducing new ones.
"The bottom line is that information of this nature should only be held if it can be demonstrated that an appropriate system of checks and balances is in place and the security of the information being stored is of paramount concern. "
The unprecedented amount of data to be stored and analysed has raised particular concerns.
Over 50 billion text messages are sent each year in the UK, and over three billion emails are sent every day.
"The database would have to manage exponentially growing volumes of 'unstructured' data," said Chris Dean, director at independent IT consultancy DWM Group.
"The huge amount of information generated by emails, phone calls and web browsing will make the task of collating and retrieving information on demand enormous.
"Unless very carefully designed [this database] could become a white elephant because of performance problems."
The proposals will face a rough ride getting through parliament. Shadow Home Secretary David Davis has referred to the database as more of a threat than a support in stopping crime, and Liberal Democrats have pledged to fight the moves.
"Ministers have taken leave of their senses if they think that this proposal is compatible with a free country and a free people," said Liberal Democrat Shadow Home Secretary Chris Huhne.
"Given its appalling track record of data loss, this government simply cannot be trusted with private information. This is an Orwellian step too far."
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