Essex Police has taken DNA samples from more than 56,000 people in three years, newly released figures show.

The force collected DNA from 17,592 last year, down from 18,432 in 2008 and the 20,015 samples taken in 2007.

The figures only emerged after new Chief Constable Jim Barker-McCardle overturned a decision to block a Freedom of Information Act request.

Essex Police was one of three forces in England and Wales that refused to answer the request, leading to Mr Barker-McCardle apologising last month.

He said that while staff had been right to refuse the request because of the number of hours it would take to respond, the sensitivity of the subject meant he would like the information to be released.

The issue is a particularly contentious one, as the DNA of people who are either not charged or later acquitted of a crime is kept on file.

Mr Barker-McCardle has admitted he will continue to keep it until the Government passes a law determining what should be done.

He said this was because he feels the issue is more serious than just the whim of each chief constable, claiming it would otherwise become a “postcode lottery”.

The force cannot say how many innocent people currently have their data on file, but has given details of the number of people who have objected to their DNA being held.

Between 2007 and 2009, only 103 people have officially requested that Essex Police removes their DNA. Of those, eight were successful in 2007, 12 in 2008 and 12 in 2009.

In a statement, Nishan Wijeratne, from Essex Police, said the retention of the information was in line with current legislation.

He said: “This is a question of law in that the law was changed to enable police to retain this information even when someone is later found innocent.

“The Criminal Justice and Police Act 2001 amended the Police and Criminal Evidence Act 1984, providing the police in England and Wales with the power to retain fingerprints and DNA samples relating to persons following acquittal at court or other discontinuance of a case.

“The Criminal Justice Act 2003 amended the Police and Criminal Evidence Act 1984 providing the police in England and Wales with the additional power to take fingerprints and DNA samples from all persons detained at a police station having been arrested for a recordable offence.”

He insisted the DNA database is a vital tool in catching criminals, particularly those guilty of serious crimes, adding: “The database is used as part of investigations, so the bigger the number of samples the greater chance of solving crime.”