Civil liberties campaigners accused the Government last night of compiling a national DNA database "by stealth" as police prepared to enter the two millionth profile into the system.
The number held has doubled in two years and a further million are due to be added in the coming year.
Police powers to keep DNA samples have been strengthened considerably since 2001 when they were first allowed to keep the information indefinitely from suspects who were not convicted.
The new Criminal Justice Bill now before Parliament extends this rule to people who are arrested but never charged.
David Blunkett, the Home Secretary, said the importance of DNA profiling to criminal detection outweighed the civil liberties objections.
"The DNA and fingerprint databases have become vital weapons in law enforcement, making our communities safer by helping to put thousands of repeat criminals behind bars," he said ahead of a lecture in London on advances in police technology.
"Every week our national DNA database matches over 1,000 DNA profiles taken from crime scenes with names on the database. Around 42 per cent of those matches are turned into detections within an average of 14 days. That is a huge achievement."
In 1998-99 there were 21,329 DNA matches and 6,151 detections. In the year to last April, there were 49,913 matches leading to 21,098 detections. The Home Office said that although only a quarter of all crimes were detected, this rises to one third where DNA has been loaded to the database.
Gareth Crossman, a spokesman for Liberty, the civil rights group, said: "The Government is hell-bent on creating a national DNA database by stealth.
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