TEENAGERS should not be recruited into the Army before they turn 18, public health campaigners have warned.

More than one in five (21 per cent) people joining the UK army are children aged 15 to 17, but experts are calling for the age threshold to be raised.

Read more: Army on standby in preparation for no-deal Brexit

The UK is the only European country and permanent member of the UN Security Council to recruit 16-year-olds.

Children as young as 15 can begin the enlistment process, with two years of training starting from the age of 16 prior to first deployment at 18.

Writing today in the journal, BMJ Open Paediatrics, the researchers from charity Medact say that current recruitment practices "capitalise on a 'window of vulnerability'" during adolescence, and disproportionately target youngsters from the lowest socioeconomic groups.

Read more: Avoidable deaths among children and teens in Scotland highest in UK

Reem Abu-Hayyeh, of Medact, and Dr Guddi Singh, an integrated child health specialist, said military service at this age exposes them to the risk of long lasting and complex effects on mental and physical health.

They said evidence shows younger recruits more vulnerable to self-harm, suicide, and alcohol misuse, associated with the isolation and culture of military life as well as the trauma of active combat.

Read more: Children's commissioner says youths from deprived backgrounds should not be targeted by Army recruitment

The British Army says it is facing a personnel shortfall of 8200 but the researchers insist the recruitment policy is "misguided and counterproductive", pointing to figures showing that those recruited under 18 account for 24% of those who leave the Armed Forces voluntarily before completing their service.

Concerns have previously been raised in Scotland about the Ministry of Defence targeting recruitment drives to schools in deprived communities.