WASHINGTON: Five months after the G20 took over as the world's official economic forum, experts are asking whether it can confront new and more pressing challenges grappling nations emerging from financial crisis.

Leaders of the Group of 20 industrialized and emerging economies have worked to address the worst financial crisis in decades but with the meltdown easing, they face challenges such as establishing a new global financial system, debt turmoil and the gradual shift in the world's economic balance of power.

"The G20 has achieved a tremendous amount in a short time but the big question is are they are going to be able to move forward from crisis mode," asked Uri Dadush, a former director of the World Bank?s global economy group.

A problem of immediate concern to the G20 is the sovereign debt crisis, stemming from Greece's battles to stop its public finances from drowning in debt that were preceded by similar problems in Iceland and Dubai.

"This problem is not confined to these economies but involves big players," Dadush, now head of the international economics program of the Carnegie Endowment for International Peace, said at a Washington forum.

Greece's debt woes highlight the problem in several bigger nations in Europe, while the United States and Japan also face sovereign debt level concerns, said analysts at the forum, "What will the G20 look like in 2050?"

The G20 summit was convened for the first time in Washington in 2008 after a US home mortgage meltdown sent a financial tsunami across the globe.

A year later, in a dramatic shift, G20 members decided to turn their group into the premier economic forum, replacing the Group of Eight (G8) comprising Britain, Canada, France, Germany, Italy, Japan, Russia, and the United States.

Aside from the G7 nations plus Russia, the G20 countries consist of Argentina, Australia, Brazil, China, India, Indonesia, South Korea, Mexico, Saudi Arabia, South Africa, Turkey and the European Union.

They represent about 90 percent of the world's gross national product, 80 percent of world trade and two-thirds of the global population.

G20 leaders also tasked the Financial Stability Board and the Basel Committee on banking supervision in April last year with developing banking reforms to prevent a collapse of the sector in the event of a new crisis.

Regulators, who want to implement these measures by 2012, notably want to strengthen rules concerning capital and private equity funds, limit debt and allow for major banks to be dismantled if they face bankruptcy.

But G20 countries such as China do not even have an open capital account yet even though it is a key player in global capital markets because of its enormous foreign exchange reserves, the world's largest.

"The key issue facing the Financial Stability Board is how to integrate financial systems in countries with open capital accounts and floating exchange rates but China is still a bit on the fringe," said Pieter Bottelier, a professor of China studies at Johns Hopkins University.

Yet, he said, China was "open minded" and "constructive in their thinking of a new financial order."

On mainly China's urging for a stronger voice for emerging powers in the International Monetary Fund, the G20 pledged to shift at least five percent of voting rights in the Fund to developing countries, Bottelier said.

Even by conservative growth assumptions, developing nations are likely to dominate the world economy in 40 years across all the major dimensions: population size, output levels, trade flows, capital flows, size of the middle class, energy consumption, and carbon emissions, the Washington forum was told.

In 2050, four of the top six economic powers will be emerging countries but developed economies will remain far richer, a report said, forecasting that in 20 years, China's GDP will be the same size as that of the United States.

"Great powers that managed the global system the last 200 years may not be doing that anymore," said James Collin, a former US ambassador to Russia.

He questioned the future of Europe as an integrated power.

"If internally divided, the adjustment may come in shocks -- politically or institutionally," he warned.

Against the new dynamic, Tim Adams, an ex-US Treasury under secretary, was concerned about the future of security forums such as NATO as well as global maritime security, such as protection of sea lanes used to ferry resources to fuel growth in developing nations.

"I also worry about how both sides are going to manage relations," citing the US and China.