US Secretary of State Antony Blinken met briefly in New Delhi on Thursday with Russian Foreign Minister Sergei Lavrov, pressing him on Ukraine in the two countries' highest-level one-on-one contact since the war.

Blinken met for less than 10 minutes with Lavrov on the sidelines of the Group of 20 talks, a day after saying that he had no plans to meet his Russian or Chinese counterparts, a senior US official said.

Blinken wanted to "disabuse the Russians of any notion that our support might be wavering" on Ukraine, the official said, after growing support from European allies for peace initiatives.

Blinken wanted to "send that message directly" and also urged Russia to engage with Ukraine on the basis of demands put forward by President Volodymyr Zelensky.

"We always remain hopeful that the Russians will reverse their decision and be prepared to engage in a diplomatic process that can lead to a just and durable peace," the official said.

"But I wouldn't say that coming out of this encounter there was any expectation that things would change in the near term."

Blinken also urged Russia to free Paul Whelan, a former US Marine detained since late 2018, and to reverse President Vladimir Putin's recent decision to suspend the New START nuclear treaty, the last arms control agreement between the Cold War-era foes.

Blinken told Lavrov that "the treaty is in the interest of both our countries as well as international security, as the world expects us to behave responsibly when it comes to nuclear security," the official said.