Russia’s demand for gas payments in roubles breaches contracts and should not be accepted, a government spokesperson for gas importer Bulgaria said on Wednesday, as a standoff between the European Union and Moscow over energy supplies intensifies.

“The Bulgarian position, which has also been coordinated on European level, is that such a breach of the existing contracts that clearly state payments should be carried out in euros or U.S. dollars, will not be allowed,” the spokesperson said.

Bulgaria meets over 90% of its gas needs with imports from Russia’s Gazprom. Its centrist government held a meeting on Wednesday to discuss what measures could be taken in the event of a halt in Russian gas supplies, the spokesperson said.

Other EU members are also scrambling to secure supplies after Moscow, angered by Western sanctions over its invasion of Ukraine that have hit the rouble, signalled it might halt gas flows if buyers didn’t pay in roubles.

The Kremlin said on Wednesday, however, that it would not immediately demand gas payments in roubles.

Bulgaria, which uses about three billion of cubic metres of gas per year, is holding talks with Azerbaijan to increase gas imports and looking into ways to import liquefied natural gas (LNG) through LNG terminals in Greece and Turkey.