Arseniy Yatsenyuk, approved Thursday as Ukraine's next prime minister, said the national economy was in shambles following nearly four months of political unrest.
"The treasury is empty," he was quoted by the Wall Street Journal as saying.
Ousted Ukrainian President Viktor Yanukovych in November decided to suspend efforts to sign free trade and association agreements with the European Union in order to protect economic ties with Russia.
Ashton met Thursday in Brussels with top European officials to discuss the next steps in the post-Yanukovych era.
A statement from her office said "Ashton made it clear that the immediate priority must be to support the stability of Ukraine, both economically and politically."
U.S. State Department spokeswoman Jen Psaki said during a Wednesday press conference Washington, as well as the International Monetary Fund, will work to see how Ukraine can chart a successful economic future.
"We and our international partners can begin to take immediate steps to help support Ukraine economically and implement the reforms necessary to restore Ukraine's political and economic health," she said.