Cops are taking DNA samples of a child almost every day in Camden, according to figures released last week.
360 children as young as 10 have been added to the National Database every year in the North London borough - regardless of whether the youngsters went on to be charged with any crime.
Jo Shaw, Liberal Democrat Parliamentary campaigner for Holborn and St Pancras, obtained the figures from the National Policing Improvement Agency under the Freedom of Information Act.
"Storing the DNA of innocent people as young as 10 is unlikely to solve crime, but it is a way of stigmatising young people. It's completely inappropriate. You are supposed to be innocent until proven guilty."
In total, there are 3,243 Camden young people on the national DNA database.
Chief Inspector Sean Wilson, of Camden police, said:
"The DNA database is a nationwide one. Legislation governing the recording and retention of DNA is adhered to by Camden police.
Home Office guidelines currently allow police to obtain DNA from persons of any age who are arrested for a recordable offence.
Persons under the age of 10 cannot be arrested as they are under the age of criminal responsibility. There is no limit to how long DNA profiles can be retained."
European Court ruling
Currently the DNA profile of everyone arrested for a recordable offence in England is kept.
However, in December, the European Court of Human Rights ruled that storing the DNA and fingerprints of innocent people was unlawful.