Gardaí are investigating an online attack that led to Irish internet users being falsely redirected to allegedly fraudulent sites when trying to access popular search engines.

Google and Yahoo's Irish domains were hit by the incident yesterday, with users taking to the web to complain that the domains had been hijacked.

It is not yet clear how the breach happened, but it is understood that it could have occurred in the IEDR's systems.

The IEDR, which is responsible for administering the registry of Ireland's dot-ie domain names, has asked the Garda Bureau of Fraud Investigation to look into the incident.

Some of the IEDR's services remained unavailable today after it temporarily took them offline on the recommendations of security experts brought in to carry out an investigation into the incident.

External web-based systems were taken off-line to perform additional analysis, but the Whois service and the IEDR's API remained fully operational, and public access to dot ie websites and email was also unaffected.