Researchers from the University of Dundee have warned about the rising misuse of a psychoactive drug that is available to buy over the internet.
Phenazepam, which was developed in the 1970s and is available on prescription only in countries of the former Soviet Bloc for treating neurological disorders, such as epilepsy, as well as for insomnia, alcohol withdrawal syndrome and anxiety, is increasingly being misused in the UK in place of illegal drugs, according to researchers.
The drug is not currently controlled in Britain, most of Europe, or America.
Recent reports from the UK, Sweden, Finland and the US describe the misuse of the drug, which can be purchased online legally.
Having identified a trend of misuse, a letter from the team discussing the issue has been published in the British Medical Journal.
After screening post-mortem blood samples in the UK since January, the Dundee team detected phenazepam in the blood in nine cases.
However, phenazepam cannot be directly identified as a cause of death in any of these cases, researchers said.
Dr Peter Maskell, a lecturer in forensic toxicology at Dundee University, said: "Like other benzodiazepines, phenazepam can be addictive and mixing with other drugs such as heroin or alcohol increases the risk of drug interaction."