“Based on observations, it was suspected that the offshore pipeline between Finland and Estonia was leaking,” the state-owned Gasgrid said in a statement.

It said that it noticed “an unusual drop in pressure” in the Balticconnector pipeline overnight, and that it is investigating along with its Estonian counterpart Elering.

Gasgrid added that the Finnish gas system was stable, with supply secured through a floating liquefied natural gas terminal (LNG) in Inkoo.

Commissioned in 2019, the Balticconnector has been the only gas import channel to Finland, apart from LNG, since Russian imports were halted in May 2022, following Moscow’s invasion of Ukraine.

Russia stopped supplying gas after Finland refused to pay in roubles, a condition imposed on “unfriendly countries” – including EU member states – as a way to sidestep western financial sanctions against Russia’s central bank.

Natural gas accounts for around 5% of Finland’s energy consumption, mainly used in industry and combined heat and power production.