The number of people injecting drugs rose by about 5,000 in three years
The number of injecting drug users in Scotland is continuing to increase, according to the latest figures.
A study by Glasgow University estimated that in 2006, 23,933 people in Scotland were injecting drugs, representing about a 30% rise on estimates for 2003.
Another report estimated that the value of the illicit drugs market in Scotland was £1.4bn, while the economic and social cost was estimated at £3.5bn.
Ministers said the figures highlighted why the new drugs strategy was needed.
The new official estimates suggest there are more than 55,000 problem drug users in Scotland, including those being prescribed the heroin substitute methadone.
While this figure is in line with previous estimates, the number of people injecting has jumped about 30% since the last time this type of data was compiled, for 2003.
The problem is worst in Glasgow, where almost 4% - or one in every 25 - of all people between the ages of 15 and 64 have a drug problem.
West Dunbartonshire, Inverclyde and Dundee also report high levels of injecting, and significant rises since the previous estimates.
Meanwhile, another report has for the first time estimated the total value and cost of the illegal drugs market in Scotland.
It suggested that heroin holds the largest share of a market worth £1.4bn, at 39%, while cannabis holds the second largest share at 19%.
The total economic and social cost of illicit drug use is estimated at £3.5bn, with problem drug use accounting for 96% of the total costs.
The costs are based on five areas; health, criminal justice, social care, costs to the economy and the wider costs to society.
Communities Minister, Fergus Ewing, said the figures underlined the need for a new approach.
"While progress is being made, it is unacceptable that some people are still having to wait months to get the help they seek," he said.
"That is why we are working closely with our partners to develop a waiting times target for services, to improve access to appropriate treatment to promote recovery from addiction.
"We have also increased our funding to NHS boards for drug treatment services to support work to tackle waiting times."
He said spending on drug treatment services would be 18% higher this year than three years ago.
Total number of users