There is evidence that the amount of heroin going into the veins of city addicts could be £1.8m annually.

Some chaotic users are taking up to £100 worth every day.

Meanwhile the number of suspected overdoses investigated by police in the city is up on last year, including three in the last 10 days.

Among them was an 18-year-old girl whose body was found in the common stairwell of a multi. A man was arrested.

“In Dundee we are seeing a steady increase in the number of suspected drug deaths that we are investigating,” confirmed Detective Chief Inspector Willie Semple, head of CID.

“Last year there were 27 such inquiries, and less than halfway through this year we are at 17, so it is certainly not reducing. The vast majority are through heroin abuse.

“We are committed to investigating these deaths, identifying where people are sourcing their drugs and reporting them to the procurator fiscal.”

Inquiries into drugs deaths are intensive, and can lead to anyone suspected of supplying the substance facing a culpable homicide charge.

Statistics covering the period between 1997 and 2006 show a 17% increase in drug-related fatalities in Tayside, a period which has coincided with huge increases in the purity of heroin on the streets.

Some has been as high as 64% pure, exposing users to risk of overdose.

“Drug deaths in Dundee and Tayside are going up, there’s no doubt about that,” said Dr Brian Kidd, chairman of the Dundee Drug and Alcohol Action Team.

“If people are using one batch and then they take another, that might have some impact on drug deaths.

“There are a lot of things that contribute to deaths, but I wouldn’t be able to say that one specific thing is causing more deaths.”