SEOUL?G20 leaders Friday gave their backing to sweeping reforms designed to give emerging economies such as China a bigger say in the International Monetary Fund.

The leaders of advanced and emerging economies announced they were delivering "a modernized IMF that better reflects the changes in the world economy through greater representation of dynamic emerging markets and developing countries."

The reforms would enhance its "legitimacy, credibility and effectiveness, making it an even stronger institution for promoting global financial stability and growth," the G20 leaders said in a summit declaration in Seoul.

The IMF's executive board had agreed the changes ? described as "historic" by managing director Dominique Strauss-Kahn ? at its own meeting last week.

They create "the biggest-ever shift of influence in favor of emerging market and developing countries," Strauss-Kahn said then.

The fund, formed after World War II to remake the world financial system and prevent a 1930s-style Depression, has long been dominated by Western powers but has faced growing calls to adapt.

The deal to reform its 24-member board of governors was thrashed out by G20 ministers last month ahead of this week's summit.

Europe has agreed to give up two seats. Just over five percent of voting rights will be transferred, and Brazil, Russia, India and China will all be among the top 10 IMF shareholders.

China will move up to the third-largest shareholder, from sixth place.

The total size of the quotas ? the contributions of the 187 member states to the fund's capital ? will be doubled, to $756 billion.

Upon his arrival at the IMF in 2007, Strauss-Kahn made quota redistribution a top priority, to resolve a long and bitter battle by emerging-market and developing countries to wrest greater power.

When a previous quota reform plan was officially adopted by member states in April 2008, Strauss-Kahn hailed it as "the beginning of the new legitimacy of the Fund."

But that reform has not been enacted due to the lack of a sufficient number of ratifications by member states.