Gazprom, the Russian energy giant, has said it is cutting daily deliveries of gas to Europe via the Nord Stream pipeline to 33 million cubic metres a day –– about 20 percent of the pipeline's capacity –– from Wednesday, leading Ukraine to call the West to action over the "gas war".

Ukrainian President Volodymyr Zelenskyy said the cuts showed that Europe should bolster sanctions against Russia. "This is an open gas war that Russia is waging against a united Europe," Zelensky said.

"They don't care what will happen to the people, how they will suffer –– from hunger due to blocked ports, from winter cold and poverty... or the occupation. These are just different forms of terror," he said in his daily video message.

"That is why you have to hit back. Do not think about how to bring back the turbine, but strengthen the sanctions," he said.

US: Russian strike on Odesa port casts doubt on grain deal

Russia's attack on the Ukrainian port of Odessa casts doubt on a grain deal, the White House has said, adding that the United States would continue to explore options with the international community to increase Ukraine exports through overland routes.

The announcement comes after the Kremlin said it did not expect the Saturday missile strike targeting military infrastructure in Ukraine would affect a plan to restart exports from the country.

"We are going to be watching this closely to see if Russia meets their commitments under this arrangement since this attack casts serious doubt on Russia’s credibility," a National Security Council spokesperson said in a statement./agencies