Slovakia, along with Hungary, stopped receiving oil from Lukoil after Ukraine banned the transit of resources from the Russian energy company last month.

The halt affects only Lukoil deliveries via the southern segment of the Duzhba ('Friendship') pipeline, which traverses Ukraine to reach the Czech Republic, Slovakia, and Hungary.

This has resulted in a 40% reduction in oil supplies for Slovakia's Slovnaft refinery, owned by the Hungarian oil and gas group MOL. The cut may also halt Slovnaft's diesel supplies to Ukraine, affecting about 10% of Ukraine's fuel consumption.

According to the Slovakian PM’s office, Fico spoke by phone with Ukrainian Prime Minister Denys Shmyhal on Saturday about, among other things, the partially halted transit of Russian oil.

"The inclusion of Lukoil on the sanctions list is just another example of senseless sanctions that do not hurt the Russian Federation but mainly some (European Union) member states, which is unacceptable," Fico was quoted as telling Shmyhal.

The Slovakian PM has long opposed sanctions against Russia and stopped direct state military aid to Ukraine after taking office last year.

While the EU has imposed sanctions on Russian crude, countries like Slovakia have exemptions to allow time to transition to alternative sources.