G20 finance ministers and central bank governors on Sunday said they "deeply regret" IMF reforms have stalled with the United States yet to ratify them.
"Our highest priority remains ratifying the 2010 reforms, and we urge the US to do so before our next meeting in April," they said in a final communique after a meeting in Sydney.
Australian Treasurer Joe Hockey, current president of the G20, said "deep disappointment" had been expressed in the room that reforms agreed in 2010 which aimed to give emerging market economies -- particularly China -- a greater say in the IMF's operations, had been held up by Washington.
"These reforms are critical to ensure that the IMF represents its entire constituency," Hockey told reporters, adding that it had moved beyond the procedural realm to become a "structural issue for the global economy".
"We urge the US to ratify the current reforms and we will review progress in April. The importance of a strong IMF is very relevant as we speak," he added, referring to ongoing unrest in the Ukraine.
He said individual finance ministers had been monitoring developments and "it is clear that there may be economic consequences to these developments".
"The IMF remains the institution best prepared to help countries in transition such as the Ukraine deal with the economic challenges if it is to request that help."
Emerging-market economies, including China and Brazil, have complained for years that their relatively small voting rights in the institution insufficiently reflect their real power in the world economy.
The failure of the United States, the largest stakeholder in the IMF, to approve the reforms has been the major stumbling block for developing countries to achieve a greater say in the Washington-based institution.
Although the White House has requested it, Congress has refused to support the reform.