A new report has undermined the credibility of the government’s £7m methadone programme, claiming drug addicts are less likely to commit crime and more likely to find work if they are forced to go through “cold turkey” withdrawal.

Research by Professor Neil McKeganey, one of Scotland’s foremost experts on addiction, revealed that half of addicts who take methadone are likely to offend, compared with less than a third of those on abstinence programmes.

It also found that those who went cold turkey were twice as likely to try to get a job.

The Scottish executive has substantially widened access to methadone as a substitute for heroin addicts. Ministers believe it is the best way to save lives and cut criminal behaviour. However, the research suggests many methadone users are topping up with illegal drugs and committing crimes to pay for their addiction.

“If you think of it as a race between these two approaches to get into employment it is clear that the abstinence approach is ahead,” said McKeganey, a director of the centre for drug misuse research at Glasgow University.

“Methadone is not a magic bullet that removes all offending behaviour.

“Work we have carried out with recovered addicts has shown that recovery has been about building an entirely new life that is not based around drugs and association with other drug users, and that is what the abstinence programmes are about.

“Methadone can leave damaged people dependent on powerful drugs for 10 to 15 years.”

Previous research by McKeganey has found that most addicts would prefer the cold-turkey approach to long-term addiction to methadone.

More addicts on pioneering cold-turkey programmes such as those offered by Glasgow’s Calton Athletic centre are on the road to recovery, but there is a shortage of treatment programmes available.

Irvine Welsh, the author of Trainspotting, starring Ewan McGregor, is among the celebrities who have backed the Glasgow centre, claiming that total abstinence is the only way to kick heroin. The centre’s work also featured in a television drama called Alive and Kicking starring Lenny Henry and Robbie Coltrane.

“We need many more agencies that have an explicit abstinence focus that will work with you from day one to take drugs out of your life,” said McKeganey.

Two months ago Michael Howard, the Conservative leader, endorsed a similar drug-free project run by the Maxie Richards Foundation in Bearsden, which is based on an uncompromising policy of deprivation. Recovering addicts are given a short course of dihydrocodeine, a pain reliever, and a range of support services designed to allow them to rebuild their lives without drugs.

The executive denied the findings undermined its approach or that it was “anti-abstinence and obsessed with methadone”.

A spokesman said it plans to expand abstinence services in future but that methadone had a strong track record for weaning addicts off heroin and would still be the best approach for many Scots. “We have to ensure that there is a range of programmes available so that individuals get the treatment best suited to them,” he said.