The number of Scots killed by drugs rose by 25% in the past year to reach the highest level ever recorded.

Figures published yesterday by the Registrar of Scotland showed there were 421 drug-related deaths in 2006, 85 more than the year before and 10% up on the previous high of 382 in 2002.

Heroin or morphine were involved in nearly 62% of the deaths, up from 58% in 2005, while the number of addicts who died with methadone in their system increased by 25 to 97, calling into question its continued use as a method of weaning heroin-users off the drug.

Ecstasy was involved in 13 deaths, up from 10 in 2005. The number of deaths linked to diazepam fell from 90 to 78. Fatalities involving cocaine also fell, from 44 to 33, despite concerns that the drug is becoming more widely used across the country.

Drug deaths in the Greater Glasgow and Clyde NHS Board area increased by 51 to 162, while Grampian saw its figure more than double from 23 to 47. All but 69 of those who died were over 25 as experts attributed the rise in deaths to the ageing of the first-generation of 1980s heroin users.

Kenny MacAskill, the Cabinet Secretary for Justice, said the statistics proved that drug abuse was "perhaps the most significant social problem of our time" and called for a "new consensus" on how to tackle the problem.

He added: "This tragic death toll highlights the true scale of the challenge we are facing. We need to improve access to effective treatment and wrap-around care and get better at educating our young people about the dangers of drug misuse, providing them with support and protection for those affected by their parents' habits.

"And we must have the right systems in place to deliver the best outcomes. Our new strategy must tackle demand as well as supply and we will place renewed focus on education, tough enforcement and, of course, new emphasis on diversion and prevention by offering more young people opportunities in sports and the arts to build self-esteem."

Yesterday's report showed that the deaths of 280 people in 2006 were directly linked to drug abuse, 76 more than in 2005.

In addition, 51 deaths were linked to accidental poisoning and 40 to intentional poisoning, while the remaining 50 were classified as "undetermined intent".

The registrar's figures go back to 1996, when the number of drug-related deaths was 244. They chart the sharp increase in heroin or morphine abuse.

In 1996, the drugs were linked to 84 deaths, but by last year that figure had more than trebled to 260.

Writing in The Herald today, one expert says the statistics show that the efforts of successive governments to tackle drug use have failed.

Neil McKeganey, who is based at Glasgow University, writes: "The hundreds of millions of pounds spent on drug abuse treatment in Scotland should by now have delivered a marked reduction in the number of addict deaths.

"Instead, we are seeing the opposite - an increase in overall addict deaths and a worrying rise in the number of deaths associated with methadone, our number one addict treatment in Scotland."

Scottish Tory leader Annabel Goldie, describing the figures as depressing and chilling, said: "We need a clearer strategy which rehabilitates those caught up in a life of drugs and helps them on the way to abstinence, while at the same time adopting a zero tolerance attitude to drugs and especially towards drug dealers."

Ross Finnie, health spokes-man for the LibDems, said efforts to steer people away from drugs must be "redoubled".

Labour MSP Hugh Henry said: "I suspect this is about more than just money and what is really needed is a radical rethink by experts working in the field."