Cllr Morwen Millson told a meeting of West Sussex County Council almost 1,000 under-18s had been added in just over three months.

She asked Cllr Lionel Barnard – the member responsible for responding on behalf of Sussex Police Authority – if he was concerned this data might now remain on record for their whole lives, regardless of whether they were ever charged with any crime.

She also asked for a view why Sussex Police had collected a higher-than-average percentage of young people's DNA.

Cllr Barnard said Sussex Police complied with national legislation and guidance.

"In summary, this states fingerprints and DNA samples may be taken by the police without consent for anyone arrested for a recordable offence – mostly offences that can lead to a prison sentence," he told the county council.

"These can be checked against the national DNA database and the fingerprint database to help the police identify suspects for unsolved crimes."

He agreed with Cllr Millson the current legislation and guidance gave rise to significant ethical issues, particularly in relation to the retention of records for children and young people.

"These issues are currently under consideration nationally, and I would not want to anticipate the outcome," said Cllr Barnard.

He was told there was no obvious reason why Sussex was marginally above the average.

What it might reflect was that, as a proportion of all people arrested in connection with recordable offences, children and young people represented a higher proportion during the period referred to.

The presence of more police officers and police community support officers on the streets was likely to deter youth crime and provide reassurance and response to calls for assistance, and also lead to more offences being recorded.