Slovakia and Hungary have increased pressure on Kyiv after they said last week they had stopped receiving oil from Lukoil via Ukraine. Hungary receives 2 million metric tons of oil from the Russian group annually, around a third of its total oil imports, Hungary’s foreign minister Peter Szijjarto said.

The two countries have initiated a consultation with the European Commission, he said, adding the Commission had three days to respond.

If the consultation procedure did not yield results, Hungary and Slovakia would take the issue to an international court of their choosing instead, he said.

The Ukrainian foreign ministry did not immediately respond to a request for comment, though the head of Ukrainian energy firm Naftogaz acknowledged a lack of oil from Lukoil.