Staff at the army’s foundation college were accused of 50 cases of assaulting or mistreating teenage recruits between 2014 and 2017, the Guardian can reveal.

Allegations made by 16 and 17-year-old soldiers or their parents and guardians about staff at the Army Foundation College (AFC) in Harrogate, north Yorkshire, included assault, battery and ill-treatment.

The revelations follow the collapse of court proceedings earlier this week against 16 AFC Harrogate instructors who had been accused of abusing recruits.

Inside the college that trains the UK's youngest soldiers Read more

During the proceedings, junior soldiers claimed they were slapped or punched, spat at, verbally abused and ordered to eat manure during a battle camp exercise in June 2014.

The case was thrown out, with a judge heavily criticising the way the Royal Military Police (RMP) had investigated the allegations and the time it took to get the case to court.

Now data obtained by the charity Child Soldiers International, which campaigns for the minimum age for soldiers to be raised, puts the focus back on the college, where almost all junior soldiers undergo training.

A freedom of information request revealed that between January 2014 and August 2017, there were 50 cases of alleged violent behaviour.

There is no detail about what happened to the staff and it is possible some may have been among those involved in the case thrown out this week. The MoD said it could not say how many individuals were involved because of confidentiality issues.

Separately, data obtained by the MP Liz Saville Roberts, the Plaid Cymru leader at Westminster, shows that in the past decade, there have been about 50 investigations conducted by the RMP into staff at the college – approximately half of them relating to assault or ill-treatment. In around 15 cases, the allegations were proven.

Rachel Taylor, the director of programmes at Child Soldiers International, said: “It is unimaginable that a sixth-form boarding school could receive 50 formal complaints of violent behaviour by members of staff in the course of three years, and not be shut down or at least subjected to serious external scrutiny.

“It takes enormous courage for a teenager to speak out against a superior officer in an intimidating environment where being perceived as weak or disloyal can be grounds for immediate dismissal and there are likely to be many more such incidents which went unrecorded.

“These figures show there is either a serious and ongoing problem of abuse, or simply that these adolescents are routinely so unprepared for the reality of army life that they believe they are being assaulted when they are actually undergoing routine training.

“This naivety is unsurprising when you recall that none of these recruits are old enough to watch a graphic war film or play Call of Duty on the Xbox. Whatever the reason is for this staggering number of complaints, it is clear that the army is a wholly unsuitable environment for adolescents and the MoD must raise the minimum enlistment age to 18 as a matter of urgency.”

Saville Roberts added: “The UK government needs to join the international community and raise the age of recruitment so that minors are no longer entering the armed forces.”

Reem Abu-Hayyeh, a peace and security campaigner at the public health charity Medact, said: “It is clear that the military does not sufficiently safeguard the wellbeing and health of minors. The UK government should join the majority of the world and stop recruiting under-18s to the armed forces.”

An army spokesperson said: “We care about our soldiers above all else and do everything we can to ensure they live and train in a safe and secure environment. All allegations of mistreatment are treated very seriously and we encourage any allegation of unacceptable behaviour to be raised. If individuals are found guilty of mistreatment appropriate disciplinary action taken will be taken.”