Several countries in Europe dependent on Russian energy suffered another with confirmation today that oil shipments have stopped through a critical pipeline.

Russian state pipeline operator Transneft said it halted shipments through the southern branch of the Druzhba oil pipeline, which flows through Ukraine to the Czech Republic, Slovakia and Hungary.

Transneft cited complications due to European Union sanctions for its action on Aug. 4, saying its payment to the company’s Ukrainian counterpart was refused.

The northern leg of the Druzhba pipeline, which runs through Belarus to Poland and Germany, was unaffected, Transneft reported.

EU leaders agreed in May to embargo most Russian oil imports by the end of the year as part of the bloc’s sanctions over Moscow’s war in Ukraine.

The embargo covers Russian oil brought in by sea but allowed temporary Druzhba pipeline shipments to Hungary and certain other landlocked countries in central Europe.

Slovakia’s oil pipeline network operator, Transpetrol, and the refining company Slovnaft confirmed that Druzhba shipments to the nation had stopped. Slovakia receives almost all its oil through the Druzhba pipeline.

Slovnaft, which is owned by Hungary’s MOL energy group, said its production has not been affected.

Slovnaft spokesperson Anton Molnar said the company and MOL were discussing with Russia and Ukraine an option for MOL, or Slovnaft, to pay the transit fees.

Slovakia’s economy minister, Richard Sulik, said he would comment Wednesday. The country has oil for about 120 days in its reserves, Sulik has said.