A former undercover police officer in the UK has spoken of his "great concern" about the harm children may suffer as a result of being used as spies in investigations.
Neil Woods, an officer with Derbyshire Police for 23 years, said being a covert human intelligence source (CHIS) is "dangerous" and organised crime gangs often subject informants to "the most extreme violence".
Mr Woods, who left the force in 2012, said he has been diagnosed with post-traumatic stress disorder as a result of undercover work he carried out during his career.
In a witness statement produced for Just for Kids Law's High Court challenge against the UK Home Office over the use of children as spies, he said: "It causes me great concern that a child could be asked to maintain a lie for any length of time and suffer the psychological harm that I have suffered.
"It has been said by some that we already have a mental health crisis looming due to the numbers of children being exploited through county lines (drugs gangs).
"I question the legitimacy in allowing the police to recruit child spies at a time when police are just beginning to recognise the lasting harm caused to adults in doing the same thing.
"Suppressing one's emotions over a prolonged period in situations of danger is psychologically damaging."