Kyiv announced in June it would tighten its sanctions regime in mid-July by preventing Russia’s second-biggest oil company, Lukoil, from using its infrastructure to export crude to Europe.

The stoppage concerns only Lukoil deliveries through the southern stretch of the Duzhba (‘Friendship’) pipeline, which runs through Ukraine to the Czech Republic, Slovakia and Hungary. Authorities in both Bratislava and Budapest said Russian crude deliveries from other suppliers were unaffected, including those transiting Ukraine.

“According to data from [Slovakian oil transporter] Transpetrol, deliveries of Russian oil to Slovakia were not stopped,” Slovakia’s Ministry of Economy said in a statement on Thursday. “The problem is, according to [Slovakian refiner] Slovnaft, deliveries of a concrete supplier, Lukoil.”

The Ministry said it was discussing the issue with its partners in Ukraine and that in the meantime Slovnaft had secured supplies from another source.

On Tuesday, Hungary’s foreign minister, Peter Szijjarto, said that while oil was flowing to Hungary from the Black Sea via the TurkStream Pipeline, Lukoil supplies via Ukraine had ceased.

“Due to a legal situation in Ukraine, Lukoil is no longer delivering to Hungary, and now we are working on a solution that would allow oil transit to restart as Russian oil is very important for our energy security,” Szijjarto said.

Industry sources cited by Reuters said crude supplies to the Czech Republic were flowing normally.