A former senior Ministry of Justice official who has written a play criticising stop and search tactics has revealed how police and government staff have put him under pressure ahead of its opening.

Dominic Taylor, an ex-policy manager at the MoJ, said he been left "uncomfortable" after receiving emails and phone calls from Metropolitan police officers and civil servants.

He said: "In the last two weeks I have taken a number of calls from both civil service and former police colleagues. Whereas we've had a bright and breezy dialogue it was suddenly chilly, absolutely chilly, as if they were fishing for information, the fear that somebody is going to blow the whistle."

The play – called Stop Search – which examines the tactic's impact on young people and features voiceovers from actor Bill Nighy and actress Siân Phillips, launches this week amid mounting concern over the contentious tactic and its disproportionate targeting of black people.

The government's own panel on the riots last summer identified stop and search as a factor in fuelling distrust among young people towards the police. New figures raise further questions over the tactic by revealing that more than a quarter of stop and searches carried out by Scotland Yard last year were against children.

Taylor is a former prison officer who while at the MoJ analysed the use of stop and search throughout the country, racial discrimination in the prison system and was invited to sit on a Scotland Yard steering committee on performance improvement before leaving last year to focus upon writing.

He added that such was the hardening of attitudes from police and Home Office staff over his play that he even began to believe he was being targeted. He cited a recent "weird" incident where an officer inspected his vehicle's tax disc but ignored other parked cars nearby.

"It was interesting that for the very first time a uniformed police officer was in our street and began checking the off-street cars in front of our house but did not check other neighbouring cars on his way in and way out. It's not particularly comfortable, time will tell how this plays out," he said.

His comments coincide with the release of statistics that show 25,291 children aged between 10 and 17 were stopped in London last year, 25.95% of the entire number. The newly disclosed data also reveals that and, on average, a youngster below the age of 10 was stopped and searched by Met officers every week.

In addition, 58 youngsters below the age of ten were targeted with just one leading to an arrest, according to the figures in the Scotland Yard "monitoring mechanism" report on the use of stop and serach.

Campaigners said they were baffled as to why children so young were being targeted, given that those under ten are not deemed legally responsible for their actions and therefore cannot be convicted of a criminal offence.

The figures relate to stop and search under Section 1 of the Police and Criminal Evidence Act 1984 and other legislation excluding section 60, which requires the authorisation of a more senior officer, because they usually involve suspicion of serious violence.

The pressure group StopWatch said the figures raised the wider issue of the criminalisation of children. The age of criminal responsibility in England and Wales was raised from eight to 10 in 1963 whereas in the rest of the European Union, 12 to 14 is more common.

Michael Shiner of the London School of Economics and StopWatch said: "We have interviewed parents who talk of having to prepare their children for being stopped and searched. What can be more perverse than a parent having to protect a child against the agent who should be there to protect them?"

Shiner, who helped research Stop Search, which opens this week in Catford, London, added: "When we were doing the research for the play we were struck by how early this stuff is starting. Young people tell us that they start to get stopped and searched as soon as they start secondary school."

Rebekah Delsol from the Open Society Justice Initiative and StopWatch said it was a concern that there was such little specific monitoring of the use of the tactic upon children. She added that the group was contemplating whether to call for regulations relating to very young children such as that they only be searched in the presence of an appropriate adult.

"We need to be clear about what lies behind these statistics. We are talking about adult strangers touching children.

She added: "Despite the regulations, some stop and searches involve intimidation and physical force. For children on the receiving end this can only be traumatic and damaging."

Taylor said that although there were some fantastic individuals in Home Office and prison system, good work was often undone by a prevailing bias. He was inspired to write Stop Search after speaking to black friends and the experiences of their children at the hands of the criminal justice system.

"There was a completely different dynamic at work, they had a fundamentally different experience."

He hopes the play - which a number of senior police officers have indicated they will attend - will have the same impact as the BBC television play Cathy Come Home. "Until then homeless people were seen as feckless ne'er-do-wells, what Ken Loach did with that brilliant script was to show there was a human dynamic going on. We hope to change the terms of discourse on how people view stop and search."