The Health Services Executive (HSE) says there is no evidence to date that heroin linked to the deaths of six Dublin drug addicts was contaminated.
However, a spokesman said toxicology tests on the drugs had not been completed and a conclusive judgment could not be made until this was done.
Seeking to allay concerns about possible contamination of heroin, the HSE spokesman said it was too early to say whether there was any connection between the deaths of the drug-users over the past week.
HSE staff were liaising with the Garda Síochána, the Dublin Coroner's office and the wider community to establish more precisely the facts surrounding the recent cluster of deaths among drug-users, he said.
"All our drugs service staff have been alerted and are advising customers. To date, no evidence of contamination had been found, as was the case in 2000 when eight drug-users died in a fortnight.
A Garda spokeswoman said they were still awaiting the result of tests being carried out on drug samples in Beaumont Hospital and that members of the force had been in contact with the families of the dead drug-users.
Gardaí are trying to establish whether the heroin used by the deceased came from the same batch. The victims were aged between 26 and 40.
Labour's Joe Costello said the deaths showed that society had failed to get the drug problem under control. He called for increased resources and manpower to tackle heroin addiction.
"The drug problem hasn't gone away. It has evolved into a new era of availability and cheaper cost. We must improve services if we are ever to combat the scourge of heroin that continues to plague many of our cities and large towns."
