U.S. Treasury Secretary Janet Yellen told Reuters that a strong statement condemning Russia's war in Ukraine was "absolutely necessary" for a communique from the G20 finance leaders' meeting in India concluding on Saturday.

Yellen said in an interview that leaving a war condemnation out of the communique would be a step back from a statement made by G20 leaders last November on the Indonesian island of Bali.

Asked whether there would be no communique from the G20 finance ministers and central bank governors meeting without such a statement, Yellen said negotiations were continuing.

The meeting on the outskirts of India's Bengaluru tech hub was due to end late on Saturday.

"I think there has to be a statement in the communique condemning Russia's war. We've had it in the past, in Bali and it's something that I think is absolutely necessary," Yellen said.

"And I think the G7 is certainly united on that, so it's something that I would expect and I think is necessary and appropriate."

Yellen's comments, however, came as hopes were fading that the group would be able to produce a joint statement in its final hours.

G20 chair India is pressing the meeting to avoid using the word "war" in any communique, G20 officials have told Reuters. India, which holds the current G20 presidency, has kept a largely neutral stance on the war, declining to blame Russia for the invasion, seeking a diplomatic solution and sharply boosting its purchases of Russian oil.

In Bali, the G20 leaders issued a statement that read: "Most members strongly condemned the war in Ukraine," signaling that Russia, a member of G20, had opposed the wording.

The Bali declaration added: "There were other views and different assessments of the situation and sanctions."