By Doina Chiacu and Patricia Zengerle

WASHINGTON (Reuters) - The United States' government said on Monday it will decide "in days" on additional sanctions if Russia does not take steps to implement an agreement to ease tensions in Ukraine reached in Geneva last week.

The steps include publicly calling on pro-Russian separatists in eastern Ukraine to vacate occupied buildings and checkpoints, accept an amnesty and address their grievances politically, State Department spokeswoman Jen Psaki said.

"If they don't take steps in the coming days, there'll be consequences," she said at a Monday news briefing. "Obviously, we would have to make a decision in the matter of - in a matter of days - if there are going to be consequences for inaction."

Some U.S. lawmakers have been clamoring for President Barack Obama's administration to impose stiff new sanctions on Russia's energy industry and major banks to encourage President Vladimir Putin to withdraw troops from the Ukrainian border and discourage further Russian incursions into Ukrainian territory.

"I think it's time to move on the next round of sanctions," Connecticut Senator Chris Murphy told Reuters on Monday, although he added that he backed giving Moscow two to three days to implement the Geneva agreement.

"I think it is important to explore diplomatic solutions when they potentially become available," the Democratic chairman of the Senate's Europe subcommittee said in a telephone interview.

"The Russians were willing to sit down in Geneva for the first time across the table from their Ukrainian counterparts, I think that discussion was worthwhile. I don't think the jury is fully in on the Geneva agreement," he said.

'GOING TO LOSE EASTERN UKRAINE'

Some members of Congress have made it clear they do not believe sanctions already in place - such as travel restrictions on individuals announced by the Obama administration - will stop Moscow.

"I think we're going to lose eastern Ukraine if we continue as we are," U.S. Senator Bob Corker, the top Republican on the Senate Foreign Relations Committee, said on NBC television's "Meet the Press" on Sunday.

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Washington and Moscow each put the onus on the other to ensure tensions are eased in the worst confrontation between Russia and the West since the Cold War.

"If there's no progress, we remain prepared, along with our European and G-7 partners, to impose additional costs. So there'll need to be decisions made in a matter of days," Psaki said.

In a telephone call on Monday, Russian Foreign Minister Sergei Lavrov asked U.S. Secretary of State John Kerry to "influence Kiev, not let hotheads there provoke a bloody conflict, and impel the current Ukrainian leadership to fulfill its obligations unflaggingly," Russia's Foreign Ministry said.

But Kerry said casting doubt on Ukraine's commitment to the accord "flies in the face of the facts," according to Psaki.

Ukraine has sent senior representatives to the east with representatives from the Organization for Security and Cooperation in Europe (OSCE), put forth an amnesty bill for separatists to give up public buildings and weapons and called an Easter pause in military operations, Kerry said.

"He asked that Russia now demonstrate an equal level of commitment to the Geneva agreement in both its rhetoric and its actions," Psaki said, such as by sending its own senior representative to work with the OSCE.

Kerry also asked Russia to join the United States in seeking the release of Imra Krat, a Ukrainian journalist being held by pro-Russian separatists in the eastern part of the country, she said.

(Additional reporting by Steve Gutterman in Moscow and Steve Holland and Patricia Zengerle in Washington; editing by G Crosse and; Bill Trott)