The EU’s chief executive on Wednesday branded as “blackmail” Russian giant Gazprom’s move to halt supplies to some European customers, but said the bloc was working on a coordinated response to Moscow’s escalation, writes Reuters.

Gazprom said it had cut supplies to Poland and Bulgaria for failing to pay for gas in roubles, Moscow’s toughest response yet to sanctions imposed by the West over the conflict in Ukraine.

“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”, European Commission President Ursula von der Leyen said.

“This is unjustified and unacceptable. And it shows once again the unreliability of Russia as a gas supplier”, - she said in a statement.

Von der Leyen said the EU was prepared for this scenario, and would continue its work to ensure alternative supplies of gas and that gas storage is filled. EU rules require all countries to have a contingency plan to cope with a gas supply shock. EU gas storage is currently 32% full.

The EU was working on a coordinated response to Russia’s escalation, von der Leyen said, and the bloc’s “gas coordination group” of representatives from national governments and the gas industry was meeting on Wednesday morning.

Poland’s climate ministry said on Tuesday its energy supplies were secure and there was no need to limit supply to consumers. The Commission has said companies should continue to pay the currency agreed in their contracts with Gazprom - 97% of which are in euros or dollars - and that paying in roubles could breach the EU’s sanctions against Russia.