Campaigners are calling for more scrutiny of police after strip-searches more than doubled over six years in Suffolk.

Authorised searches leapt from 525 in 2011 to 1,378 in 2017, when 11% resulted in items being found.

Five of 64 searches involving exposure of intimate body parts resulted in found items since 2011.

The force said it would ask volunteers to examine the use of powers following a 55% increase in suspects removing some or all clothing in custody since 2016.

Under the Police and Criminal Evidence Act, anyone over 10 can be strip-searched for evidence or an object that could cause harm.

From 2011 to 2016, 272 searches were authorised on under 18s.

Tim Hawke, founder of Ipswich and Suffolk Respect, Equality and Fairness (ISREF), which conducted the research, said: “If the police are wrong 88% of the time, they are either abusing their powers or have an atrocious sense of judgement – meaning they shouldn’t make such decisions until they get better training.”

Mr Hawke wants more scrutiny of the law – like that conducted by an independent panel on the use of stop-and-search powers.

Joint head of custody, Chief Inspector Kersty Brooks said: “It’s important to point out that strip searches are not used to find evidence to arrest someone. We only do it when we have evidence or intelligence to act on.

“A search can be authorised if someone is brought in for possession with intent to supply drugs; their demeanour alerts an officer to the possibility they may be concealing something; or we have intelligence that someone has tried to harm themselves in custody or at home.”

She said a report into Suffolk’s custody suites had highlighted that some searches were being recorded as strips when they involved anything beyond a pat-down or emptying pockets.

“I want to make sure people are safeguarded in custody, but I am concerned by the number,” added Ch Insp Brooks, who has asked the police and crime commissioner’s Independent Custody Visiting Scheme to provide more scrutiny.

“I want to establish why we have a low hit rate, and would like to see the positive rate go up because it can be a useful tool” she said.

“I believe detailed analysis may suggest that more crime is lending itself to the requirement for a strip-search, like drug offences.

“It’s very rare to get children as young as 10 in custody, and they would have to be particularly troubled for us to carry out a strip search.”

Mr Hawke has raised the issue at public meetings organised by police and crime commissioner Tim Passmore, who said his accountability and performance panel would soon be presented a full year’s worth of data to assess.

Mr Passmore added: “This is a relatively new area of focus to us, so it’s important we have the correct mechanisms in place for scrutiny.

“This is a legitimate policing tactic but we have to be sure it’s used in a proportionate way. At the moment, we need more information and clarification to ensure that’s the case.

“We need evidence and justification to make sure it doesn’t undermine public confidence.

“No one’s trying to hide away from this, but we must be careful not to jump to conclusions.

“We were faced with this issue around stop-and-search use, and are now regarded as having best practice across all forces.

“That volunteers are willing to provide independent assessment, without vested interest, should be reassurance to anyone concerned.”