WASHINGTON — US President Barack Obama and top European leaders are moving ahead on a new round of sanctions against Russia, US officials said Friday amid hints they could come within days.

US sanctions could be imposed as early as Monday, a source close to the issue told AFP, asking not to be identified, but warning the situation in Ukraine remained fluid.

German Chancellor Angela Merkel said EU foreign ministers would meet soon to discuss the issue after speaking by conference call with Obama, British Prime Minister David Cameron, French President Francois Hollande and Italian Prime Minister Matteo Renzi.

“Given the absence of progress, we have to think about — and not just think about, but act on — the option of new sanctions,” Merkel said.

“For this purpose, European Union foreign ministers will meet as soon as possible.”

US State Department spokeswoman Jen Psaki told reporters Washington had been working in “lockstep” with the Europeans.

“It’s safe to say we’re in the stage of not just preparing but coordinating on sanctions and what’s next.”

It likely that the third round of sanctions against Russians and Ukrainians blamed for the unrest in the former Soviet satellite will again target individuals and entities.

Both US and EU officials have already blacklisted more than a dozen individuals including the breakaway leaders in Crimea, annexed by Moscow last month.

Obama said earlier Friday during a visit to Seoul that Washington had already lined up more targeted sanctions against Russia “that are ready to go.”

But he also signaled the new sanctions would not involve an attempt to target key areas of the Russian economy such as mining, energy and the financial sectors.

US officials have said those measures would only be considered if Russia sent its regular forces across the border into eastern Ukraine.

“The heads of state and government have called for a rapid reaction by the G7 and raised the prospect of new sanctions by the international community against Russia,” the French presidency said in a statement.

US lawmakers, including some who visited Ukraine in recent days, also called on Obama to follow through with his sanctions threat.

Republican Senator Bob Corker said Russian President Vladimir Putin was “only emboldened by empty rhetoric, so it is time for the administration to back up their talk by immediately putting in place tough sanctions against Russian banks and energy companies.”

Fellow Republican John McCain, who lost the White House election to Obama in 2008, lamented a lack of action “capable of changing President Putin’s calculus and behavior.”

“The cost of this in Ukraine is a perception of weakness that President Putin clearly interprets as a license to commit further acts of aggression,” he said.

Senate Democrat Carl Levin, speaking in Kiev after meeting Prime Minister Arseniy Yatsenyuk, urged Obama to “make more robust use” of his powers to authorize sanctions “to ensure that Putin pays a price for his illegal actions against Ukraine.”