Russia says it would consider any US move to curb the operations of Russian banks or their foreign currency dealings a declaration of economic war.

The US announced a new round of sanctions on Wednesday targeting Russia that pushed the ruble to two-year lows and sparked a wider sell-off over fears Russia was locked in a spiral of never-ending sanctions.

"It would be needed to react to this war economically, politically, or, if needed, by other means," Russia's prime minister said. "And our American friends need to understand this."

MOSCOW — Russia would consider any US move to curb the operations of Russian banks or their foreign currency dealings a declaration of economic war, Prime Minister Dmitry Medvedev said on Friday.

The US on Wednesday announced a new round of sanctions targeting Russia that pushed the ruble to two-year lows and sparked a wider sell-off over fears Russia was locked in a spiral of never-ending sanctions.

Separate legislation introduced last week in draft form by Republican and Democratic senators proposes curbs on the operations of several state-owned Russian banks in the US and restrictions on their use of the dollar.

Medvedev said Moscow would take economic, political, or other retaliatory measures against the US if Washington targeted Russian banks.

"I would not like to comment on talks about future sanctions, but I can say one thing: If some ban on banks' operations or on their use of one or another currency follows, it would be possible to clearly call it a declaration of economic war," Medvedev said.

"And it would be necessary, it would be needed to react to this war economically, politically, or, if needed, by other means. And our American friends need to understand this," he said, speaking on a trip to the Russian Far East.

The fate of the bill he was referring to is not certain.

The full US Congress will not be back in Washington until September, and even then congressional aides said they did not expect the measure would pass in its entirety.

While it was difficult to assess so far in advance, they said it was more likely that only some of its provisions would be included as amendments in another piece of legislation, such as a spending bill Congress must pass before September 30 to prevent a government shutdown.