The decision by Russian energy giant Gazprom to restrict gas supplies to Bulgaria and Poland is yet another effort at blackmail, according to European Commission Chairperson Ursula von der Leyen on Wednesday.

Gazprom announced earlier in the day that it had entirely terminated gas supplies to Bulgargaz, Bulgaria's largest natural gas distribution firm, and PGNiG, Poland's oil and gas company, due to the companies' failure to pay for gas in rubles.

"The announcement by Gazprom that it is unilaterally stopping delivery of gas to customers in Europe is yet another attempt by Russia to use gas as an instrument of blackmail. This is unjustified and unacceptable. And it shows once again the unreliability of Russia as a gas supplier," von der Leyen said in a statement.

The EU is prepared for this situation and is in close contact with all member states, according to the commission chief, who also stated that the bloc has been "drawing out... coordinated EU response."

"Europeans can trust that we stand united and in solidarity with the member states impacted." 

Earlier today, Russia's Gazprom announced the suspension of gas supplies to Bulgaria and Poland due to the non-payment of dues in rubles after it announced on Wednesday that it had completely suspended gas supplies to Bulgaria's largest natural gas distribution company Bulgargaz and Polish oil and gas company PGNiG, as the companies failed to pay for gas in rubles.

Bulgaria and Poland have both said they will be able to make up the shortfall from other sources. 

"We have been working to ensure alternative deliveries and the best possible storage levels across the EU," von der Leyen said in a statement.

"Member states have put in place contingency plans for just such a scenario and we worked with them in coordination and solidarity," she continued.

"A meeting of the gas coordination group is taking place right now."