Trafficking in heroin and cocaine, particularly crack cocaine, poses the greatest single threat to the UK in terms of the scale of serious organised criminal involvement, the illegal proceeds secured and the overall harm caused.

Home Office estimates put the harm caused by Class A drugs at around £13bn a year. This largely arises from the profits from sales, the crimes addicts commit to fund their habit, and the damage caused to family life and communities, as well as from costs to addicts' health.