The EU will coordinate a joint response against Russia following the decision on the stopped gas supplies, says EU Commission President Ursula von der Leyen.

She also promises a sixth sanction package.

- That the Russian leadership would use the gas market as a political weapon was expected.

It is unacceptable and it shows once again how unreliable Russia is as a gas supplier, she says in an official statement.

So far, Poland and Bulgaria have been stopped from trading Russian gas.

The Russian energy giant Gazprom threatened on Wednesday to cut off gas supplies to more European countries if trading is not done in Russian currency rubles.

- We will do everything to ensure that Gazprom's decision has the least possible impact on European consumers, von der Leyen says.

"Trying to blackmail the country"

The Polish government accuses Gazprom of breach of contract and said it will take legal action against the gas supplier.

Prime Minister Mateusz Morawiecki says Russia is trying to "blackmail" the country.

He sees the measure as revenge for new sanctions that Warsaw has imposed on Russia, reports the news agency AP.

Bulgaria also accuses the Russian government of blackmail and breach of contract.

Prime Minister Kiril Petkov says the country will respond by reviewing all agreements with Gazprom, including those regarding so-called transit agreements for Russian gas delivered to Serbia and Hungary.

Both Poland and Bulgaria are important transit countries for further exports of Russian gas.

Gazprom has warned that it will choose other transport routes if they in any way illegally affect deliveries.

Germany: No gas stop signals

Germany, which is heavily dependent on Russian gas, still sees no indication that Gazprom would stop deliveries to the country.

This is stated by Prime Minister Kiril Petkov, according to Reuters. 

Slovakia, which imports 85 percent of its gas from Russia, states through Finance Minister Richard Sulik that the country does not risk being shut out of the Russian gas market, according to Reuters.

Russia accounts for 40 percent of the gas market in Europe.

Gazprom's announcement caused the gas price to skyrocket on Wednesday, according to Bloomberg.