The Prime Minister, after visiting the headquarters of the Forensic Science Service in London, dismissed concerns over privacy and said most people wanted the biggest possible database.

He said: “Politicians are more resistant (to the database) than the public. The public think, if this is helping us track down murderers, rapists . . . then go for it.”

Asked whether there should be any restrictions on the number of people whose DNA was stored on the database, Mr Blair said: “The number on the database should be the maximum you can get.”

The Prime Minister provided a sample of his own DNA for the database several years ago, Downing Street said. A total of 18,000 people have followed suit by voluntarily donating samples.

The national DNA bank, set up under the Criminal Justice Act 2003, has 3.6 million DNA profiles, equivalent to 6 per cent of Britain’s population of 60 million.

Civil liberty campaigners reacted with dismay to Mr Blair’s comments.

Shami Chakrabarti, director of Liberty, said: “The project of turning a nation of citizens into one of suspects may well be the legacy sought by the Prime Minister.”

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