An association of European electricity companies has confirmed that hackers have breached its office network.
"ENTSO-E has recently found evidence of a successful cyber intrusion into its office network," the association said in a statement.
It added that a risk assessment had been performed and contingency plans are now in place to reduce the risk and impact of any further attacks.
ENTSO-E, or the European Network of Transmission System Operators for Electricity, represents 42 electricity transmission system operators (TSOs) from 35 countries across Europe.
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These TSOs are the organisations that are responsible for the bulk transmission of electric power on the main high-voltage electric networks, like National Grid ESO in the UK.
"It is important to note that the ENTSO-E office network is not connected to any operational TSO system. Our TSO members have been informed and we continue to monitor and assess the situation," said ENTSO-E.
The association plays a key role in developing the pan-European grid and achieving the ambitious European decarbonisation, according to its website.
It's not clear who targeted the association's network or why. However, hackers have been increasingly interested in energy companies in recent years for a number of reasons.
"Electric energy-associated organizations are at risk for network intrusions and continue to be compromised globally," noted security company Dragos.