Russia is halting its supply of natural gas to Finland, the Finnish state-owned energy firm Gasum says.
Finland has been refusing to pay for its supplies in roubles. But it also follows an announcement that Finland will apply for Nato membership.
Gasum said the move was "regrettable" but said there would be no disruption to customers.
Despite the Ukraine conflict, Russia continues to supply gas to many European countries.
After Western powers sanctioned Russia over the war, Russia said "unfriendly" countries must pay for gas using the Russian currency, a move the EU considers blackmail.
Reliance on Russian energy is a contributing factor in the cost-of-living crisis faced by many consumers.
Finland imports most of its gas from Russia but gas accounts for less than a tenth of the country's energy consumption.
"It is highly regrettable that natural gas supplies under our supply contract will now be halted," said Gasum CEO Mika Wiljanen.
"However, we have been carefully preparing for this situation and provided that there will be no disruptions in the gas transmission network, we will be able to supply all our customers with gas in the coming months," he added.
Asked about the matter, a Kremlin spokesman said "it is obvious that nobody is going to deliver anything for free".
On Sunday, Russia also cut electricity supplies to Finland. It had threatened retaliation should Finland apply to join Nato.
In a separate development, Russia's state-owned oil company Rosneft said on Friday that former German Chancellor Gerhard Schröder had informed them he would no longer serve on their board.
Mr Schröder has faced increasing public outrage over the lucrative role. He has refused to criticise Russia's President Vladimir Putin over the conflict, who he counts as a personal friend.
