The panel, which included European Union foreign policy chief Javier Solana, former US Secretary of State Madeleine Albright and former World Bank President James Wolfensohn, argued that the G8 has become "outdated."

"The leadership and mandates of key international institutions, from the G8 to the U.N. Security Council, have not kept pace with the new powerholders and dynamic threats of a changed world," the Managing Global Insecurity Project said in a report.

"Traditional powers cannot achieve sustainable solutions on issues from economic stability to climate change without the emerging powers at the negotiating table," said the group, formed by the Brookings Institution think tank and by research centers at New York University and Stanford University.

The report recommended expanding the G8, which is comprised of Britain, Canada, France, Germany, Italy, Japan, Russia and the United States, to include Brazil, China, India, Mexico and South Africa. It also proposed adding Indonesia, Turkey, Egypt or Nigeria to create a Group of 16.

Thomas Pickering, a former US undersecretary of state for political affairs, said some nations might resist seeing their own influence diluted but said solving some problems required a broader range of actors.

"Rather than to argue about the size of the table and the number of people present, it would be much better to take the view that if a country has a substantial contribution to make to the resolution of the problem ... then they probably ought to be at the table," he said.