Police can keep storing the DNA profiles of thousands of children and young people, ministers have decided.
None of the 24,000 were charged with an offence or cautioned
Tory MP Grant Shapps last month pressed for the details of 24,000 under-18s never cautioned, charged or convicted to be removed from the police database.
He claimed a national DNA database was being created by stealth.
But Home Office Minister Andy Burnham has announced DNA profiles will continue to be stored, saying the samples are helping to catch criminals.
Police have been able to collect DNA samples and fingerprints from people they arrest for more than 20 years.
And since 2001 they have been able to keep the DNA profiles even when people are not cautioned, charged or convicted.
'No personal cost'
About 200,000 DNA samples, including 24,168 from under-18s, have been stored which would been destroyed before the changes to the rules.
In a written statement to Parliament, Mr Burnham said those DNA samples had been matched to crime scenes in more than 8,000 offences, including murders and rapes.
And early research showed taking samples from people who were not charged had led to "matches" with stains at crime scenes in more than 3,000 offences, 541 of them involving under-18s.
200,000 DNA samples kept from people never charged or convicted, including 24,168 from under-18s
Those samples matched to 3,000 crime scenes, including 541 involving DNA from under-18s
£300m spent on database
Mr Burnham said the figures showed there was a "clear public benefit" to keeping the samples and the existing policy was justified.
"Inclusion on the database does not signify a criminal record and there is no personal cost or material disadvantage to the individual simply by being on it," he argued.
The minister stressed there were no children under 10 on the database whose DNA samples had been taken without the agreement of their parent or guardian - something which was in any case not allowed.
He said chief constables had been given guidance on dealing with requests from the samples to be taken off the database in exceptional circumstances.
Last month Mr Shapps outlined fears that a huge juvenile database - though not illegal - was being created by the "back door".
After Mr Burnham's latest statement, he urged the government to "come clean" and have a clear debate if it really wanted to create a national DNA database, starting with children.
He discovered the number of DNA samples being stored when he was he was campaigning to have the details of 14-year-old Jack Saywood, who was the victim of mistaken identity, removed from the database.
Critics of the current policy claim it encourages police to arrest people so they can get their DNA samples. This can cause discrimination of people from ethnic minorities, they argue.
Lib Dem spokesman Lynne Featherstone said the guidance given to police chiefs on removing DNA from the database did not go far enough.
"We need to know if the government is creating a database of everyone in the country by stealth or if the database will only be used to store the profiles of criminals," she said.