Northamptonshire Police have taken DNA samples from about 10 children a week in the past few years, figures have shown.
The Howard League for Penal Reform, which obtained the figures, says youngsters as young as 10-years-old have had samples taken from them after being arrested by officers.
Officers took DNA swabs from 496 children and teenagers aged under 17 in 2011, and took 666 swabs in 2010.
Included in those are three swabs taken from 10-year-olds and 13 swabs taken from 11-year-olds.
Under current rules, police can retain indefinitely the DNA of anyone they arrest for a recordable offence – although new legislation due to come into force later this year means the police will not be able to hold the DNA records of children arrested but not convicted.
Frances Crook, from the Howard League for Penal Reform, said: “Children who get into trouble with the police are usually just up to mischief.
“Treating them like hardened criminals by taking DNA seems excessive.”
Northamptonshire Police have also revealed that 11 people in the county have had records removed from the National DNA Database since 2008.
The force says it has had 63 applications to have details removed, but only 11 of those were deemed to be “exceptional” cases which merited approval.
A police spokesman said applications to remove DNA from the national database were dealt with on a case-by-case basis.
She added: “There isn’t one rule which deems what we would consider to be an exceptional case so it isn’t possible to easily define.
“Every time we receive an application to have details removed it is dealt with on its own merits.”
The Telegraph asked Northamptonshire Police how many records it had on the national database, but was told the force does not manage the facility and the information would only be available through a Freedom of Information request.