G7 finance ministers and central bank governors are to meet on Thursday and Friday in Germany, with the Russian invasion of Ukraine high on their agenda.

Yellen said the United States has made a strong commitment to Ukraine funding and it was clear that the EU was "very serious about wanting to provide the necessary aid as well."

"We'll need to look to other partners in the G7 -- to Japan, Canada, the UK -- to contribute as well, but I do believe that the European Union will make a significant contribution," she said.

Yellen also said the United States would support the European Union's efforts to impose an embargo on buying Russian oil and said the ban on purchases phased to start next year, could be combined with tariffs.

"These are two things that could be combined," Yellen told reporters in Brussels. "It might be possible to combine a phase-out with a price mechanism. But there are a lot of options here. It is critically important that they reduce their dependence on Russian oil," she said.

(Reporting by David Lawder, writing by Jan Strupczewski)