Ukraine has halted Russian gas supplies to European customers through its pipeline network, almost three years into Moscow’s all-out invasion.

The move comes after a prewar transit deal expired during the final hours of 2024 and as the continent braces itself for a plunge in temperatures that could hasten the drain on gas reserves.

Ukraine’s energy minister, Herman Halushchenko, confirmed on Wednesday morning that Kyiv had stopped the transit “in the interest of national security” after Russia refused to alter its stance on the war.

“This is a historic event,” he said in an update on the Telegram messaging app. “Russia is losing markets and will incur financial losses. Europe has already decided to phase out Russian gas, and [this] aligns with what Ukraine has done today.”

Gas prices have surged in the last four months in anticipation of the switch-off and the prospect of plummeting temperatures in Europe this winter.

Russia was once the continent’s biggest supplier of gas but it has lost almost all of its EU customers since the war began, as buyers across central Europe have turned to the US, Norway and Qatar for supplies.

At a summit in Brussels last month, Ukraine’s president, Volodymyr Zelenskyy, vowed that Kyiv would not allow Moscow to use the transits to earn “additional billions … on our blood, on the lives of our citizens.” But he had briefly held open the possibility of the gas flows continuing if payments to Russia were withheld until the war ended.

Russia’s Gazprom said in a statement on Wednesday that it “has no technical and legal possibility” of sending gas through Ukraine, due to Kyiv’s refusal to extend the deal.

The pipeline had been established when Ukraine and Russia were both part of the Soviet Union.

Even as Russian troops and tanks moved into Ukraine in 2022, Russian gas kept flowing through the network to Europe, under a five-year agreement that allowed Gazprom to earn money from the gas while Ukraine collected transit fees.

Ukraine may be able to meet its own gas demand after the cutoff under normal weather conditions by relying on homegrown fossil fuel production and storage, but the International Energy Agency has said a colder-than-average winter could increase the amount of gas Ukraine needs to import from the EU.

The forecast cold snap later this week is already shaping up to be one of the toughest tests for Europe’s gas markets in recent years, coming after a period in which reserves have been burned up at the fastest rate since the energy crisis began.