Kremlin-based hackers reportedly targeted Ireland's power grid in another cyberattack on UK's critical infrastructure.
Although there is no evidence to suggest that Irish energy networks were disrupted, security experts reportedly believe hackers stole data, including passwords, and may have gained access to internal networks.
They also said that Ireland, which is home to the European headquarters of major American tech giants such as Facebook, Apple and others, is being used as a testing ground by Russian hackers.
The Times reported that it is believed the hackers who attempted to infiltrate the Irish power grid have ties to Russia's intelligence agency GRU.
The Russian hacker group Fancy Bear, which is widely believed to be responsible for the cyberattacks targeting US democratic parties during the 2016 presidential elections, has also been previously linked to the GRU.
However, it is still uncertain if the cyberattack against Irish power networks was the work of Fancy Bear hackers.
The ESB reportedly refrained from commenting on the matter, saying it doesn't make public "specific operational details" of its cybersecurity.
"Security of the electricity supply is a key priority for ESB. As such, all threats to the supply are treated with the utmost seriousness," a spokesman said.
Ireland's National Cyber Security Centre, however, confirmed that it was working on the matter.
Earlier this month, US authorities said that Russian hackers had targeted American nuclear and power companies.
According to security experts, similar cyberattack techniques were used against firms in Ireland, adding that hackers may also target UK firms operating nuclear and power networks.
The Times reported that the recent wave of attacks is an attempt by Russian hackers to infiltrate critical infrastructure, specifically the energy networks.