Home secretary Jacqui Smith has set out plans to give the police and security services more powers to gather phone and e-mail data.
She said the police risked losing the ability to fight crime and terrorism without the new laws.
The government plans a giant database to store details of every UK phone call and e-mail sent by citizens.
The plan will be included in a new Communications Data Bill, due to be introduced in the Queen's Speech next month.
In a speech to the Institute of Public Policy Research, Smith said, "Our ability to intercept communications and obtain communications data is vital to fighting terrorism and combating serious crime, including child sex abuse, murder and drugs trafficking.
"Communications data - that is, data about calls, such as the location and identity of the caller, not the content of the calls themselves - is used as important evidence in 95% of serious crime cases, and in almost all security service operations since 2004."
Smith said the database would help keep the authorities one step ahead of the criminals and terrorists, and said the fact the content of the phone conversations and e-mails would not be recorded in the database should reassure citizens.
Government terror watchdog Lord Carlile has already expressed opposition to the database, saying it could be "open season" on collecting data on citizens.
The Information Commissioner has also said such a plan could breach the Data Protection Act.
The data trust blog: Concern over giant database, you bet!