As it became illegal to light up in bars and restaurants, pot users were told they can still smoke joints in Amsterdam’s cannabis cafes  – as long as they don’t contain tobacco.

Anti-drugs spokesman Gus Van Tiel said: “They’ll be smoking neat cannabis. When we’re trying to reduce the potency of drugs, it is insane.”

Inspectors will patrol the country’s 750 pot coffee shops to ensure people are smoking only pure marijuana.

A government spokesman said: “The law is to protect non-smokers from the effects of tobacco smoke.

“Inspectors can tell if a joint is pure or mixed with tobacco.”