Speaking at the spring meetings of the IMF and World Bank, the group said the failure after five years of the US Congress to ratify the reforms was undermining the effectiveness and legitimacy of the global crisis lender.
"We reiterate our deep disappointment with the lack of progress in implementing the IMF quota and governance reforms agreed to in 2010 and strongly urge the US to complete ratification," they said.
"This remains an impediment to IMF credibility, legitimacy and effectiveness and has considerably delayed forward-looking commitments," they added, pointing to a second set of reforms that had been expected this year.
But the US Congress has refused to sign off on the deal, with some legislators not wanting to contribute more money to the IMF and others concerned about any erosion to the dominant US role at the fund.
Also Read
Criticisms of Washington have steadily grown, and IMF Managing Director Christine Lagarde said Thursday that she understood why other IMF members "are frustrated and impatient to see that reform actually implemented."
The G-24 endorsed the "Plan B" put forward in recent weeks to split the the two facets of the 2010 reforms and put through the quota revision without the need for ratification by the US Congress.
The net effect of that reform would be to reduce the voting power of European countries while increasing that of China, India and others.