Gardaí have not had any reports yet of the toxic ecstasy batch outside Cork, but warn that it could turn up at any time.
Garda sources said they hoped users who have this brown crystalline powder will heed the alert issued by the HSE and dispose of it.
Detectives are making good progress in identifying the origin of the powder and have questioned a leading drug supplier in Cork about it.
The powder contained high-purity MDMA, the main ecstasy chemical, and PMMA, an amphetamine derivative.
"Two people dying at the same time after ingesting the same powder has caused serious concern," a Garda source told the Irish Examiner.
"The main objective with the alert is to stop people taking it. There is a danger other people in Cork have it, that’s there’s more around and we could have a recurrence."
He added: "We have no evidence of this elsewhere [outside Cork], but it could turn up tomorrow. These things don’t stay localised for too long."
It has also emerged that two other people had severe reactions after ingesting the toxic batch at the party in Kinsale.
It is understood they had extremely high temperatures afterwards, but, according to sources, "managed to pull through". Gardaí have spoken to these people.
Gardaí have not seized this brown powder form of ecstasy before, but know of its presence elsewhere in Europe. Small quantities of PMMA powder were seized here last year.
Gardaí said there are a huge range of drugs available on the internet. Last June, officers seized 10kg of a drug called MEC, a synthetic stimulant powder similar to some of the legal highs formerly available in head shops.