"What I want to say is in the past month or so the US has been taking a defensive stance on the issue and become more and more isolated," he said. "The US should review its stance on this issue."

Leo Melamed, chairman emeritus of the Chicago Mercantile Exchange, said the US has been too slow in accepting the necessity of the AIIB in the Asian world. Its position contrasts with other Western economies, which actively sought to engage in the architecture and cowrite the rules.

Jenny Shipley, former prime minister of New Zealand, said her country, the first developed nation to join the AIIB as a founding member, hopes to be involved in drafting the bank's operating rules.

"The bank should face up to the future and not be excessively focused on what happened in the past," Shipley said, adding that New Zealand will propose a set of rules before the end of this year.

The bank could be innovative in how it works with other multilateral financial institutions, how the board is constituted and how loans are made, she said. For example, board members need not be resident board members, as is the case with the International Monetary Fund and World Bank.

Shaukat Aziz, former prime minister of Pakistan, agreed, saying it is a blessing that the AIIB starts from square one, and it shoudn't be "a hostage to history".

Panelists from the Chinese side kept a lower profile. Li Ruogu, former chairman of the Export-Import Bank of China, said the frequent comparison of the AIIB and the Bretton Woods system is "not appropriate" — referring to the monetary system of major industrial states that emerged in the mid-20th century.

He said the primary goal of the AIIB is to fill the shortage of funding for Asia's badly needed infrastructure. An additional $8 trillion is needed to fund infrastructure in Asia to maintain the current economic growth to 2020, according to a previous estimate by the Asian Development Bank.

"The priority now is to formulate the articles of association as quickly as possible. We would also like to see concrete projects," Li said.

He cautioned that people should have reasonable expectations about the commercial yields likely through AIIB investments, which will be poured into long-term projects.

Hu Huaibang, chairman of China Development Bank, said the AIIB should achieve the regional development target through commercial operations, and to achieve sustainability the fiscal balance is crucial.

"If financial institutions for development fail to abide by rule of low profit, they can't be sustainable," he said.