Campaign groups have warned that the UK is becoming "increasingly isolated" internationally in continuing to recruit people below the age of 18 into the armed forces.
A report by Child Soldiers International and ForcesWatch found:
- It cost an estimated minimum of £88,985 to recruit and train each new soldier aged 16 to 17-and-a-half, compared with £42,818 for each adult recruit, including salary costs
- Initial training for minors lasted either 23 or 50 weeks, depending on the recruit's trade, but enlisting adults could complete the phase one course in 14 weeks
- The drop-out rate for minors was 36.6% compared with 28.3% for adults but under-18s who complete training are likely to serve for 10 years rather than the 7.6-year average for over-18s
More top news
More than 1.85 million people have called for the US president's visit to be watered down to avoid causing "embarrassment" to the Queen.
Jim Mattis arrived in Baghdad on the day after US-backed Iraqi forces launched an operation to reclaim Mosul from IS.
The scale of the blood poisoning disease sepsis is "far worse" than previously thought thanks to a "crippling" lack of data, a study says.