The HSE has confirmed that sensitive data relating to approximately 520 patients was posted on the dark web last week.
The data was illegally accessed in the ransomware attack two weeks ago, and includes patient details, minutes of meetings and correspondence with patients.
The HSE begun the process of notifying patients involved.
The Financial Times reported last week that they had seen medical and personal information about Irish patients shared online. The HSE today confirmed that this data was an early release of information by hackers as samples to prove that they had confidential information.
“The data was the initial small trance of data that was previously reported on, and we are not aware of any further attempted publication of our data,” the HSE said.
“We apologise for the inconvenience caused to out patients and service users. The HSE is working with An Garda Siochana on this criminal investigation.”