The Health Service Executive is investigating the discovery of hundreds of confidential patient files in a landfill site in Glounthaune, Co Cork.
The medical records - which date back to before 1983 - contain patient names, addresses, dates of birth, details of medical conditions, diagnoses and treatments.
They were discovered when part of the landfill site was excavated during the preparatory works for the re-opening of the East Cork railway line.
The files are from patients who were treated at Cork Regional Hospital, which has since been renamed as Cork University Hospital, and at St Finbarr's Hospital.
They include laboratory reports, accident and emergency records, prescription sheets and correspondence between family doctors and medical specialists.
The HSE said it was working in co-operation with the construction company and that HSE security staff have secured the area where the files were uncovered.
In a statement, the HSE insisted all medical records since 1983 have been "confidentially archived and stored by a professional data storage company". It said all records since the mid-1980s are stored indefinitely. None are disposed of.
"Prior to that, certain inactive hospital records would have been sent for microfilming and then for appropriate disposal," the statement said. "The HSE is currently undertaking an in-depth investigation to establish the facts and determine how these files were disposed of inappropriately."
HSE representatives are meeting Cork County Council staff at the site today.
A Garda spokeswoman confirmed this morning the discovery is being investigated.
Speaking this afternoon, Fine Gael health spokesperson Dr James Reilly said public reassurance was needed to ensure that this did not happen again.
“The discovery of these confidential, medical files is disturbing and it is right that a thorough and timely enquiry should take place into how it occurred. While the system may have changed since these documents were disposed of, there is no way that they should have been sent to landfill intact. The HSE must ensure they are dealing with reputable suppliers and have proper protocols in place for waste disposal," said Dr Reilly.