Finland’s state-owned energy company Gasum said Friday that Russia would soon cut off the country’s main source of natural gas supplies, forcing it to find alternatives.

Russia’s Gazprom PJSC informed the company that it would stop delivering natural gas supplies to Finland beginning Saturday (May 21). Gazprom said it was halting exports to the country for its failure to comply with a process to pay for natural gas deliveries in rubles.

Gazprom said Friday that it had not received payment for April deliveries and would not export any gas to the country until it complies with the Kremlin’s decree for ruble payments. Gasum said it would not cooperate with the requirement because it violates its long-term supply contract with Russia and announced earlier in the week it was...