Russia has threatened to suspend or terminate a natural gas supply agreement with Armenia if authorities in Yerevan continue to pursue closer ties with the European Union.

Foreign Ministry spokeswoman Maria Zakharova warned in a Telegram post on Wednesday that Russia is prepared to unilaterally cancel a 2013 bilateral agreement that guarantees Armenia duty-free deliveries of natural gas, petroleum products and rough diamonds.

Her warning comes after Armenia’s infrastructure ministry denied having received an official letter from Russian Energy Minister Sergei Tsivilev threatening to rip up the agreement.

Zakharova insisted the Russian Embassy in Yerevan delivered the letter earlier on Wednesday. She mockingly suggested that Armenia’s infrastructure minister check with officials at his own foreign ministry to get filled in.

Armenian Prime Minister Nikol Pashinyan later on Wednesday rejected the ultimatum.