European Commission President Ursula von der Leyen accused Russia of trying to “blackmail” the bloc with gas, after Russian energy giant Gazprom halted supplies to Poland and Bulgaria on Wednesday.

“Gazprom's announcement is another attempt by Russia to blackmail us with gas. We are prepared for this scenario. We are mapping out our coordinated EU response,” von der Leyen wrote on Twitter.

“Europeans can trust that we stand united and in solidarity with the Member States impacted.”

In a separate statement, von der Leyen said a meeting between the EU's gas coordination group was underway to map out a response.

Some context: Gazprom halted gas supplies to Poland and Bulgaria after both countries refused to pay in rubles. Russia had warned “unfriendly” countries last month that they would need to pay for gas in the Russian currency starting April 1, or risk being cut off.

The payment spat threatens gas supplies that have continued to flow, even as Russian troops shelled major cities in Ukraine and the West imposed crippling sanctions on Russia's economy.

The EU is planning to slash the consumption of Russian natural gas this year as it prepares for a complete break with its single biggest energy supplier. But Europe would struggle to survive for long without Russian gas, and finding alternative sources presents a huge logistical challenge.