Britain's government was accused on Tuesday of breaking a promise to stop keeping the DNA records of people arrested for crimes but later found innocent.

Britain's DNA database is one of the largest in the world, containing genetic profiles of more than five million people, or 8 per cent of the population. Samples are taken from everyone arrested for a crime, and the information is usually retained even if the person is acquitted or freed without charge.

Critics of the practice including Alec Jeffreys, the scientist who discovered DNA fingerprinting say it unfairly taints hundreds of thousands of innocent people with the suggestion of guilt.

After an outcry from civil libertarians and a ruling from the European Court of Human Rights, the government last year promised to delete the DNA profiles of up to 1 million innocent people. Legislation outlining how that will be done is currently going through Parliament.

But a government minister has said that while the physical DNA samples of innocent people will be deleted and their electronic profiles removed from the country's central database, some profiles could still be kept by local forensic science labs, albeit with the names removed.

A Home Office spokesman said that is because the profiles of the innocent are stored at the labs alongside those of convicted criminals and it would be "impractical" to sort them out.