But they are rejecting the European Commission’s proposal to use spare capacity on the JANAF Adriatic pipeline in Croatia to supply both countries with oil not sourced in Russia.

“Croatia is simply not a reliable country for transit,” Hungary’s Foreign Minister Péter Szijjártó said. “Oil transit prices were raised fivefold since the outbreak of the (Ukraine) war by Croatia.”

Péter Szijjártó had previously called the sanctions an “unacceptable step”.

“It is a politically deeply offensive statement that we did not expect from the representative of the country to which ill-intentioned moves we have long responded with extreme restraint and moderation,” Croatia’s Foreign Minister Gordan Grlic Radman said.

While Slovakia, whose Hungarian-owned Slovnaft refinery already takes some oil via JANAF, also known as Adria, said it had received a letter from the Croatian government offering to secure supplies.

“But for what price? What capacity? No one knows that today,” Slovak Foreign Minister Juraj Blanar said in a statement.

Earlier this month, just days after Hungary took on the rotating presidency of the Council of the EU, the chief of staff of Prime Minister Viktor Orban travelled to both Ukraine and Russia in what he called a “peace mission”.

This prompted outrage among EU officials, who stressed Mr Orban was not representing Brussels in his trip to the Kremlin.