A new study reveals vast quantities are being made for export by state-trained scientists in collusion with corrupt officials and criminal gangs in a country desperate for hard currency.

Inevitably, it has ended up creating a catastrophic epidemic back home. In some parts of the country up to 50 per cent of the population are reported to be hooked.

The study discloses drug abuse has reached ‘remarkable proportions and keeps growing, engulfing new social groups and regions’.

The inquiry, by two South Korea-based academics, is based on interviews with 21 recent defectors. It confirms earlier evidence from the US and China, where there are soaring levels of crystal meth addiction in border regions with North Korea.