Several countries in Europe dependent on Russian energy suffered another blow with confirmation Tuesday 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.

"The following days will show if it's another escalation of the energy war by Russia or a technical problem about payments," Czech Industry and Trade Minister Jozef Sikela said.

Slovakia's economy minister, Richard Sulik, previously said his country has enough oil in its reserves for about 120 days.

Russia has also curtailed natural gas shipments to Europe after most countries refused to abide by Russian President Vladimir Putin's wartime order requiring payments in rubles instead of dollars or euros.

Correction:

Backstory: