By Gram Slattery and Andrew Gray

WASHINGTON (Reuters) - U.S. President Donald Trump urged EU officials on Tuesday to hit China with tariffs of up to 100% as part of a strategy to pressure Russian President Vladimir Putin, according to a U.S. official and an EU diplomat.

Trump also encouraged the European Union to slap India with similarly expansive tariffs, said the official, who requested anonymity to discuss private conversations.

China and India are major purchasers of Russian oil and, as such, they play a vital role in keeping Russia's economy afloat as it continues to pursue its expanded invasion of Ukraine, which began in 2022.

Trump made the request, which was conveyed via conference call, to EU sanctions envoy David O'Sullivan and other EU officials. The EU delegation is currently in Washington to discuss sanctions coordination.

The EU diplomat said the U.S. had indicated it was willing to impose similar tariffs if the European Union heeded the U.S. request.

"They are basically saying: We'll do this but you need to do it with us," the diplomat said.

The U.S. request, if heeded, would result in a change of strategy for the EU, which has preferred to isolate Russia with sanctions rather than tariffs.

China firmly opposes the U.S. applying such so-called economic pressure, its foreign ministry said at a regular press briefing on Wednesday, adding that it also opposed the using of China in discussions on Russia.

Trump, whose request was first reported by the Financial Times, has frequently threatened to impose tariffs on India and China as punishment for their purchases of Russian crude.

While Trump did hike tariffs on India over the summer by 25 percentage points in part due to its economic relationship with the Kremlin, Trump has yet to pull the trigger on the more punishing options he has floated.

At times, he has complained that Europe itself has not fully decoupled from Russia, which supplied about 19% of EU gas imports last year although the bloc says it is committed to fully ending its dependency on Russian energy.

Later on Tuesday, Trump suggested that the U.S. could in fact boost trade with India, writing in an evening social media post that the U.S. and India are working to address trade barriers between the nations. He added that he was looking forward to speaking with Indian Prime Minister Narendra Modi.