The HSE has confirmed that the data of around 520 patients has emerged online following its cyber attack.
In a statement, the executive says sensitive information about patients has been shared along with minutes of meetings.
The HSE is now working to identify the patients involved and says it will work to inform them as soon as possible.
This update relates to a leak that was previously reported by the Financial Times - the HSE says it's not aware of any further attempts to publish data.
Investigation
The HSE says: "Recently a news publication wrote a story saying they had seen HSE data that had been illegally accessed. We informed the publication of the court order we obtained in relation to this matter last week and asked them to supply it to us, and they agreed.
"We have examined it and can confirm it is HSE data relating to approx 520 patients, as well as some corporate documents. The data includes sensitive patient data, minutes of meetings and correspondence with patients.
"The HSE's Data Protection Office has followed the appropriate procedures, including notifying the relevant health service providers and the Data Protection Commission.
"The process of notifying the patients involved has commenced. This will involve some further analysis of the data, and we will do this as quickly as possible.
"This data was the initial small tranche of data that was previously reported on, and we are not aware of any further attempted publication of our data.
"We apologise for the inconvenience caused to our patients and service users. The HSE is working with An Garda Síochána on this criminal investigation."
