Multinational tech companies operating here are being warned they are the most likely targets of a large-scale attack by a spying bug.
Complex malware designed to collect information about people and organisations has been discovered.
Symnatec, the internet security company which claims to have found the bug, says it can take screenshots, control the cursor and steal passwords.
Regin is highly sophisticated software which has been active since 2008 and may have been created by a national government.
It has been used to attack individuals and small businesses as well as private companies, government entities and research institutes.
Telecoms companies have also been infected, allowing hackers to gain access to phone calls.
It is highly sophisticated and may have taken months or even years to complete.
Computers can be infected with the software through means including fake internet sites and instant messenger programmes.
It is unusually low-key, meaning that it can be used on a target for several years before being noticed.
A report released by Symnatec claims Ireland has been the site of 9% of confirmed infections and Russia, Saudi Arabia and Mexico have also been heavily affected.
The report describes the purpose of Regin as “intelligence gathering” and says: “It is used for the collection of data and continuous monitoring of targeted organisations or individuals.”