The Health Service Executive has said it does not know how many confidential medical files have been dumped in fields in Co Cork, or how they got there.
The confidential files were discovered earlier this week near the village of Glounthaune near Cork city.
The area where they were found is a former landfill site.
The HSE said today that it is investigating the discovery of the files with the utmost urgency, saying it should not have happened.
The files contain detailed medical histories of people who were treated at Cork Regional Hospital, the hospital now known as Cork University Hospital, and at St Finbarr's Hospital in the city.
Data includes the names, addresses, dates of birth and medical conditions of patients treated in the 1970s and early 1980s.
It is believed they were recently uncovered during excavation works for the construction of a commuter rail link.
The area has now been secured and fencing is being erected around it.
Personnel from the HSE and Cork County Council have been on site.
Dumping ceased on the site in the early 1990s.
A historic landfill team from Cork County Council was scheduled to conduct an investigation there before the discovery, but it had not been considered a high priority.
The HSE is operating a phoneline for people who may have concerns following the discovery of the files. The number is 1850-742-000.