Treatment services in England have made slow progress in increasing the numbers of people they get off drugs, despite a £130m rise in their budget.
Currently, less than 3% of users emerge from treatment drug-free
Spending on drugs services rose from £253m in 2004-05 to £384m last year, National Treatment Agency figures show.
But the numbers emerging from treatment free of addiction have barely changed. Three years ago, 5,759 left drug-free compared with 5,829 last year.
The Department of Health said the figures "distort the true picture".
BBC home editor Mark Easton said fewer than 3% were drug-free after treatment.
The government had always maintained treatment was not just about getting people off drugs - it also cut crime, improved health and helped users get their lives straight, our correspondent added.
The government is committed to getting people into "effective treatment" which can do something to make their lives better which has "benefits for wider society".
However, he said analysis of the recently published figures showed the proportion of people getting off drugs after treatment had fallen from 3.5% three years ago to less than 3% now.
And the figures meant that the cost of getting each person off drugs over this three-year period worked out as £1.85m.
Mr Easton also said that the government's 10-year strategy, due to be launched next April and about which a statement is due soon, is "about getting more people off drugs".
Danny Kushlik, from the pro drug-legalisation charity Transform, said that treatment was not about achieving abstinence.
"What we know from all the evidence is there's only a tiny proportion of any addict group, whether it be addiction to alcohol, tobacco, cocaine or heroine, who at any one point give up," he said.
"The generally recognised figure is about 5% so it's crazy to expect anything greater in terms of abstinence from a treatment intervention."
Earlier this month, it emerged that heroin and cocaine addicts on the same government treatment programme were being given drugs as a reward for clean urine samples.
The National Treatment Agency's own survey of almost 200 clinics in England found users were being offered extra methadone, a heroin substitute, or anti-depressants for good behaviour.
It admitted the practice was "unethical" and offering drugs for anything other than clinical need was wrong.
Health minister Dawn Primarolo asked for a report into the survey.
A spokesperson for the Department of Health said: "In the last few years, there has been a massive expansion in the numbers entering drug treatment.
"It generally takes between five and seven years for an addict to successfully complete their treatment, and therefore it would be unrealistic to expect to see the results of this expansion in treatment immediately.
"Getting users into treatment and keeping them there is the best way to save their lives and reduce the harm they cause to people around them and to society.
"We have made important progress in recent years. There are now over 195,000 people accessing drug treatment every year, 130% more than in 1998."