Two Irish websites have been subjected to suspicious activity this evening.
The sites concerned are those of the Labour Party and Irish Aid, which is run by the Department of Foreign Affairs.
The Labour Party said that its website was unavailable for a time this evening after it came under cyber attack.
It said the website was overwhelmed with requests from an automated system in what is known as a "denial of service" attack.
The party says the website has not been hacked and it has very secure systems.
Meanwhile, the Irish Aid website was taken offline after suspicious activity was discovered.
The Department of Foreign Affairs said: "We are aware of website user login information being posted online.
"The website server has been taken offline as a precautionary measure and the matter is being investigated by our IT specialists.
"This is an external service and is separate to the internal Departmental servers; these have not been affected."