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By Andrea Shalal

NUSA DUA, Indonesia, July 15 (Reuters) - U.S. Treasury Secretary Janet Yellen condemned Russia's "brutal and unjust war" in Ukraine and said Russian finance officials taking part in a G20 meeting in Indonesia on Friday shared responsibility for the "horrific consequences" of the war.

Yellen, speaking at the opening session of the gathering of Group of 20 finance ministers and central bankers on the Indonesian island of Bali, welcomed Ukraine's finance minister and blamed the negative spillovers of the war "solely" on Russia, a Treasury official said.

Russian Deputy Finance Minister Timur Maksimov was in Bali for the meetings, while Finance Minister Anton Siluanov was participating virtually when Yellen spoke, a source familiar with the matter said.

Yellen told reporters on Thursday that Russian officials had no place at this week's meeting of the Group of 20 major economies, and called on the global community to hold Russia accountable for the war and its dramatic impact on energy prices and rising food insecurity.

The U.S. finance chief urged G20 members to scale up and accelerate financial assistance to help Ukraine, whose finance minister Serhiy Marchenko was present at the opening session.

"I condemn Russia’s brutal and unjust war in the strongest possible terms," Yellen said. "By starting this war, Russia is solely responsible for negative spillovers to the global economy, particularly higher commodity prices."

She said Russian officials participating in the meeting were "adding to the horrific consequences of this war through their continued support of the Putin regime."

"You share responsibility for the innocent lives lost and the ongoing human and economic toll that the war is causing around the world," she said, addressing the Russian officials.

Yellen is pushing hard for other countries to back a proposed cap on the price of Russian oil to help lower energy prices and maintain global oil flows after European and potentially British and U.S. sanctions on the transport of Russian oil take effect at the end of the year.

Failing to adopt such measures, she told reporters on Thursday, would shut in a significant amount of Russian oil and drive global oil prices higher.

It was not immediately clear if Western officials would leave the room when Russian officials spoke, as they did in Washington during the last meeting of G20 finance officials. (Reporting by Andrea Shalal; Editing by Tom Hogue and Michael Perry)