Slovakia’s Prime Minister Robert Fico threatened on Saturday to cut off emergency electricity supplies to Ukraine unless Kyiv acts within two days to resume the pumping of Russian oil to Slovakia over Ukraine's territory, cut off for nearly a month.

Slovakia, along with Hungary, is one of just two EU countries that still rely on significant amounts of Russian oil shipped via the Soviet-era Druzhba pipeline over Ukraine. Both also have leaders that have maintained close relations with Moscow, bucking a largely pro-Ukrainian European consensus.

Russian oil through the main Druzhba pipe has been cut off since January 27, when Kyiv says a Russian drone strike hit pipeline equipment in Western Ukraine. Slovakia and Hungary have become increasingly vocal this week in demanding it resume.

Slovakia, meanwhile, is also a major source of European electricity for Ukraine, needed as Russian attacks have damaged its grid. Energy sector experts say Slovakia provided 18% of record-setting Ukrainian electricity imports last month.

“If oil supplies to Slovakia are not resumed on Monday, I will ask SEPS, the state-owned joint-stock company, to stop emergency electricity supplies to Ukraine,” Fico said in a post on X.

Ukraine has proposed alternative transit routes to ship oil to Europe while emergency pipeline repair works are under way. In a letter seen by Reuters, the Ukrainian mission to the EU proposed shipments through Ukraine's oil transportation system or a maritime route, potentially including the Odesa-Brody pipeline linking Ukraine's main Black Sea port to the EU.

“Ukraine consistently reiterates its continuous readiness to ensure transportation of the oil within the available legal framework,” it said.

Since October last year, Russia has intensified its drone and missile attacks on the Ukrainian energy system, knocking out electricity and heat and plunging millions of Ukrainians into long blackouts during bitterly cold winter temperatures.

Throughout the war that began with the full-scale Russian invasion whose fourth anniversary falls on Tuesday, Ukraine has allowed its territory to be used for Russian energy exports to Europe, which have been sharply curtailed but not halted.