A proposed communications database containing details of everybody's telephone calls, emails and internet use could be run by a private firm, it was claimed last night.

The option to tender out the management of the controversial database will be included in a consultation paper to be published next month, according to the Guardian.

The facility is designed to help police and the Security Service by ensuring they have access to vital communications data which may not by saved by telephone or internet providers.

The plans have already come under fire from civil liberties campaigners.

But Sir Ken McDonald stepped up his attack in light of the Guardian's report, dismissing the notion that additional legal assurances would ensure the information is not misused.

He told the paper: "All history tells us that reassurances like these are worthless in the long run. In the first security crisis the locks would loosen."

The database, which critics claim would cost up to £12 billion, is not intended to feature the content of communications, but only the details of internet sites visited and what emails and telephone calls have been made, to whom and at what times.

Currently the information has to be requested from communications companies, but it is not always readily available.

A Home Office spokesman said: "The communications revolution has been rapid in this country and the way in which we collect communications data needs to change so that law enforcement agencies can maintain their ability to tackle serious crime and terrorism.

"To ensure that we keep up with technological advances we intend to consult widely on proposals in the New Year.

"We have been very clear that there are no plans for a database containing the content of emails, texts or conversations."