Scotland is the worst country in the world for drug-related crime, according to an international study.

The United Nations found there were 656 drug offences per 100,000 people in Scotland. Second-placed Iran recorded 619 per 100,000.

The figures, which compared drug-related crime, possession and abuse across more than 70 states, put Scotland's drug crime rate at more than double that of England and Wales, and six times the worldwide average.

Experts and opposition parties described the statistics, from a survey by the United Nations Office on Drugs and Crime, as "horrifying".

Former director of Scotland Against Drugs, Alistair Ramsay, said: "This report should act as a wake-up call to the government. There has been a huge rise in problematic drug users in recent years and we know many of them fund their habit through crime.

"The fact is the way drugs are tackled needs a radical shake-up. We need a proper, co-ordinated strategy."

Bill Aitken, justice spokesman for the Scottish Conservatives, said: "These are horrifying figures and it is clear action is long overdue.

"Practically all crimes such as shoplifting, housebreaking and car theft are related to a need to feed a drug habit. It may be that much tougher action is necessary in the years ahead."

However, Gordon Meldrum, director general of the Scottish Crime and Drug Enforcement Agency, insisted that the war on drugs was being won.

He said: "The latest Scottish Crime and Justice Survey shows encouraging signs that more people in Scotland are living their lives  free from the influence of drugs. We have better intelligence than ever before and more hard drugs are being intercepted closer to source before they are cut into multiple street-level deals."

A Scottish Government spokesman said that the administration was investing record amounts in justice as well as delivering the highest number of police to fight serious crime.