Mr McConnell said the executive were tackling supply and demand

In the last quarter of 2005, nearly 400 addicts had waited over a year.

The SNP's deputy leader Nicola Sturgeon said the waiting times were "just not acceptable" as she presented them to MSPs during First Minister's Questions.

However, Jack McConnell said funding for rehabilitation programmes had "significantly increased".

He said the Scottish Executive was following a strategy of tackling both supply and demand.

"That is why drug education programmes and drug rehabilitation programmes are so important, and that is why we have so significantly increased resources for both," he said.

'Justifiable situation'

Ms Sturgeon acknowledged that there had been success in tackling the supply of drugs and the attempts to improve rehabilitation and treatment.

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However, she said addicts had to be assessed before they could be treated.

"Two years ago, 30% of addicts referred for treatment had to wait more than three weeks for assessment," she said.

"Is the first minister concerned, as I am, that the official statistics show over 50% of addicts now have to wait more than three weeks to be assessed for treatment?"

The first minister said that priority had been given to cutting assessment and treatment waiting times in other areas of the health service and that had triggered an increase in other waiting times.

"That would be in the short-term, at least, a justifiable situation, but it would not be justifiable in the long-term," he added.