More than 100,000 DNA records have been placed on a national database by Thames Valley Police.

Police chiefs held 106,051 different genetic profiles when a survey was carried out in July.

The figure - which includes Oxfordshire - was revealed by Home Secretary John Reid in response to a Parliamentary written question from an MP.

Most of the profiles were of people over the age of 21. But the Thames Valley database also contains files on 4,000 children aged between 10 and 16; 5,000 teenagers aged between 16 and 18; and more than 7,000 people aged 19 to 21.

In March, the Oxford Mail reported how the database included the genetic details of 102 under 18s from the region who have never been convicted, charged or cautioned.

The database has expanded significantly over the last five years, following Government and police investment of more than £300m.

It has now become the largest of any country in the world. More than five per cent of the UK population is logged compared with 0.5 per cent in the USA.

In total, about 3.5 million profiles are retained nationwide. Almost three million of the profiles are for people over 21 and 140,000 are from children under 16. A controversial amendment to the law in 2001 allowed police to hold samples of people who have been arrested but not cautioned or charged with any offence.

Conservatives accused the Government of building a "DNA database by stealth" - including the genetic information of people found innocent of any crimes.

The Government rejected demands that police be made to delete samples taken from under 18s who are arrested but subsequently released.

Former Home Office minister Andy Burnham insisted the relaxing of the law had allowed the police to match teenagers' samples to evidence from unsolved offences.