Washington/Moscow/IBNS: The United States has raised "concerns" over its "strategic partner" India's ties with Russia after Prime Minister Narendra Modi met Vladimir Putin in an informal meeting at Moscow, media reports said.

Speaking to the reporters, US State Department spokesperson Matthew Miller said, "We did just see Modi, like (Hungarian Prime Minister Viktor) Orban, meet with (Ukrainian) President (Volodymyr) Zelenskyy. We thought that was an important step to take.

"And we would urge India, as we do any country when it engages with Russia, to make clear that any resolution to the conflict in Ukraine needs to be one that respects the UN charter, that respects Ukraine's territorial integrity, Ukraine's sovereignty."

"India is a strategic partner with whom we engage in a full and frank dialogue. And that includes our concerns about their relationship with Russia," Miller said.

"I will look at Prime Minister Modi's public remarks to see what he talked about. But as I said, we made quite clear directly with India our concerns about their relationship with Russia.

"So we would hope India and any other country, when they engage with Russia, would make clear that Russia should respect the UN charter, should respect Ukraine's sovereignty and territorial integrity," the spokesperson added.

End Ukraine war: India's appeal to Russia

India has made a direct appeal to Moscow to end the over two-year-long war against Ukraine during Modi's informal meeting with Putin at the latter's residence, media reports said.

Modi, who is on a two-day visit to Russia, is believed to have told Putin as quoted by NDTV, "India has always called for respecting the UN Charter, including territorial integrity and sovereignty.

"There is no solution on the battlefield. Dialogue and diplomacy is the way forward."

Earlier, India refused to condemn Russia, with which New Delhi shares a warm relationship for decades, for its launching of attack on Ukraine and also abstained from United Nations' resolutions censuring the country. 

After concluding his Russian trip, Modi will head to Austria.