China said on Thursday that its purchases of Russian oil were legitimate and decried "unilateral bullying" by the United States, as President Donald Trump pushes countries to stop buying fuel from Moscow over the war in Ukraine.

Trump said on Wednesday that Indian Prime Minister Narendra Modi had promised him New Delhi would stop buying Russian oil, adding that he will get China to follow suit.

India neither confirmed or denied it was shifting its policy.

Trump has accused both China and India of funding the Ukraine war through the purchases, and has also demanded that European allies immediately stop buying oil from Russia.

Asked on Thursday about Trump's intention to pressure China further, the Foreign Ministry defended its "normal, legitimate economic, trade, and energy cooperation with countries around the world, including Russia".

"The actions of the United States are a typical example of unilateral bullying and economic coercion," Foreign Ministry spokesman Lin Jian said at a press briefing.

If China's interests are harmed, it will "take firm countermeasures and resolutely safeguard its sovereignty", he warned. (AFP)