Fingrid, Finland’s national grid operator, said Estlink 2 was down but the damage “does not threaten the operation of the electricity system” in the country.
Repairs are expected to take “several months.”
“On our part, we are investigating a serious diversion,” said Robin Lardot, director of Finland’s National Bureau of Investigation (NBI).
President Alexander Stubb announced on X that authorities had received an “overview” of the cable breach.
He stressed the need to “prevent the risks” posed by vessels that are part of the shadow fleet.
Finnish police said the case was being investigated as “aggravated hooliganism”.
The damaged cable had a transmission capacity of 650 megawatts and a length of 170 km (105 mi), 145 km of which is underwater. The fault was discovered on Thursday in the underwater part.
The EU threatened to impose new sanctions on Russia as a result of the incident and said it was “stepping up efforts to protect submarine cables”.
“We strongly condemn any deliberate destruction of Europe’s critical infrastructure,” said a joint statement by the European Commission and the EU’s high representative for foreign policy, Kaia Kalas.
