India is a strategic partner with whom it engages in a full and frank dialogue, the United States has said as it urged New Delhi to make clear to Russia that any resolution to the conflict in Ukraine must respect the UN charter, Ukraine's territorial integrity and sovereignty.

State Department Spokesperson Matthew Miller said this on Monday when he was asked about Prime Minister Narendra Modi's ongoing visit to Russia and his meetings with Russian President Vladimir Putin.

"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.

"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," Miller said at a press briefing.

"I will look to 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," he said in response to another question.

India has been stoutly defending its "special and privileged strategic partnership" with Russia and maintained the momentum in the ties notwithstanding the Ukraine conflict.

India has not yet condemned Russia's invasion of Ukraine in 2022 and consistently pitched for a resolution of the conflict through dialogue and diplomacy.

Putin on Monday night welcomed Modi at his official residence at Novo-Ogaryovo for a "private engagement". Top sources said that India's stand is that a 'solution cannot be found on the battlefield', indicating that the Ukraine conflict figured prominently during their informal talks.

On Tuesday, Modi will co-chair the 22nd India-Russia annual summit with Putin.

The focus of the 22nd India-Russia annual summit is likely to be boosting bilateral cooperation in the areas of energy, security, trade, investment and people-to-people exchanges.

This is Modi's first trip to Russia since its invasion of Ukraine more than two years ago.