The European Commission (EC) has confirmed it was targeted by a cyber attack ahead of a significant summit in Brussels.
An EC spokesperson told IT PRO it had detected attacks targeting the EC as well as the External Action Service, which effectively acts as the EU's foreign ministry.
Despite reports indicating the attacks were serious, the spokesman claimed they had not caused any serious impact on operations.
The spokesman said the threat was not "necessarily related" to the summit, which takes place this week and will focus on a number of critical situations, including the Libyan crisis.
Employees had been asked to change their login passwords to the EC network, whilst email was temporarily shut down as officials investigated the attacks.
The spokesman would not give any further details on the nature of the threats.
The news comes just weeks after the French Ministry was attacked, in which more than 150 computers were compromised.
Some sources have indicated the tactics used in both cases were similar.
Mikko Hypponen, chief research officer at F-Secure, said it was "highly likely" the two attacks came from the same source.
Despite this, Hypponen was dismissive of relating the attacks to cyber warfare.
"Cyber attacks, certainly. But I don't see a war," he told IT PRO.
"Espionage has always been happening, during times of war and peace. Nowadays it's obviously done with computers, as the information is no longer on paper - it's data."
As claimed by various security experts, the whole concept of cyber war has been over-hyped.
