Youths with no criminal record are being targeted for arrest so their DNA can be logged on a database in the event they commit crimes.
A total of 386 under-18s had their DNA taken and stored by police last year in one north London borough – more than one a day.
An experience officer working for the Metropolitan Police admitted the DNA was being stored as part of a ‘long-term crime prevention strategy’.
The officer said: ‘We are often told that we have just one chance to get that DNA sample and if we miss it then that might mean a rape or a murder goes unsolved in the future.’
He added: ‘Have we got targets for young people who have not been arrested yet? The answer is yes.
‘But we are not just waiting outside schools to pick them up, we are acting on intelligence.
‘If you know you have had your DNA taken and it is on a database then you will think twice about committing burglary for a living. Already this year some 169 under-18s have had their profiles uploaded.’
The officer, who asked not to be named, made the astonishing admission after a Freedom of Information request reveal the startling figures in Camden in London.
LibDem parliamentary candidate for Holborn and St Pancras, Jo Shaw, obtained the figures and was shocked at the findings.
Ms Shaw said: ‘Storing the DNA of innocent people as young as 10 is unlikely to solve Camden’s crime problems, but is a costly way of stigmatising young people.
‘If you’re innocent, you shouldn’t have your data kept for years. DNA samples, which are taken by police after an arrest is made, are turned into a number known as a profile and are kept on a national database indefinitely.’
Camden’s representative at the national Youth Parliament, Axel Landin, said: ‘Building a catalogue of people they think will be prominent criminals in the future sounds like a renegade justice system.
‘Someone who is not convicted of a crime is no more guilty in the eyes of the law than someone who has never been investigated so their DNA should be destroyed.
Chief Inspector Sean Wilson, of Camden Police, said: ‘The DNA database is a nationwide one.
‘Legislation governing the recording and retention of DNA is fully adhered to by Camden Police.’
New Government proposals state that youngsters who have only been arrested once for minor offences and been found not guilty will have their DNA profiles destroyed when they reach 18.