Tim Adams, the Treasury's undersecretary for international affairs, said the agreement was only the first step towards more comprehensive change after the IMF's annual meeting in Singapore this month.

Adams said he was "pleased" with the pact reached by International Monetary Fund directors late Thursday to give a greater say in Fund decision-making to China, South Korea, Turkey and Mexico.

He said the agreement, which should be formally adopted at the Singapore meetings of the IMF and World Bank on September 19-20, acknowledged "the rapid growth in emerging markets and the evolution of economies around the world".

"However, there is much important work left to be done after Singapore and it is crucial that the Fund's membership approach this endeavour in the spirit of re-making the Fund to look like the face of today's global economy.

"The IMF management and membership now need to demonstrate that the institution will move swiftly to fundamental reform in step two," Adams said.

The United States wants an IMF member's voting power to reflect its gross domestic product, arguing that without reform, the Fund risks irrelevance. The US share of votes would also go up under that formula.

The 184-member Fund, which was set up at the end of World War II and lends money to countries in deep economic difficulties, remains dominated by the United States, European countries and Japan.

Despite its growing stature as a global economic powerhouse, China has only slightly more IMF votes than Belgium.

IMF managing director Rodrigo Rato agreed that the quotas, which determine members' access to financing and votes, needed urgent reform.

"I think that all members recognise that relevant quotas and voting shares do not adequately respond to the reality of the world economy," he told Asia-based reporters in an online briefing late Thursday.

However, a further-reaching overhaul of the IMF's decision-making remains more elusive with countries in Europe said to be reluctant to lose some of their existing influence.