Joining the Asian Infrastructure Investment Bank (AIIB) would be a good investment for the United States, a prominent economist said.

David Dollar, a senior fellow at the John L. Thornton China Center of the Brookings Institution, made the remarks on Tuesday evening during the annual China Town Hall held by the National Committee on US-China Relations.

Dollar, a former World Bank official and US Treasury official, was the local speaker at the Confucius Institute US Center, just across the street from the Brookings, before former Secretary of State Henry Kissinger made a live-webcast keynote speech to the town hall.

Dollar was in favor of the US joining the AIIB right from the beginning. He said that there was a large number of serious and well-known people who think positively about the AIIB, naming former Fed Chairman Ben Bernanke, former Treasury Secretary Hank Paulson and former World Bank President Bob Zoellick.

He admitted that it would be tough to get the Congress to appropriate the money for the US to join the China-led AIIB. "It would take a pretty big educational effort on the part of any administration," Dollar said, triggering laughter among the audience.

"I think that would be a good investment," he added.

Aside from the anti-China sentiment among some US lawmakers, the Republican-controlled Congress has a generally uncooperative relationship with the Obama administration.

US officials, including Undersecretary of Treasury Nathan Sheets on Tuesday, now speak more positively about the AIIB in contrast to their rhetoric earlier this year, when the US was seen as trying to dissuade its close allies - Australia, South Korea and the UK in particular - from joining the AIIB.

Dollar said the AIIB has the potential to quickly grow to the size of the World Bank.

"It's off to a good start," he said, referring to the $509 million in investments approved by AIIB board in late June for four projects.

Three of the four projects are co-financed with the World Bank, the Asian Development Bank, the United Kingdom Department for International Development and the European Bank for Reconstruction and Development. They include a power grid in Bangladesh, slum renovation in Indonesia and highway construction in Tajikistan and Pakistan.

Amy He in New York contributed to this story.

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