Finance minister Lou Jiwei said China's contribution to the proposed Asian Infrastructure Investment Bank is open to adjustment, depending on how many countries join the project.

"China's investment in the bank does not have to reach 50 percent," Lou said in an interview with Xinhua this week.

"If many countries take part, our investment could correspondingly decrease, but by economic weight, China is still expected to hold the biggest share."

President Xi Jinping proposed setting up the bank during a visit to Indonesia in October 2013, with a view to promoting regional integration.

China has held three rounds of talks with interested countries, and a memo is due to be signed this autumn.

"We are actively discussing a founders list, basic framework and regulations to put the bank into operation as soon as possible," Lou said.

The size of the bank's capital and investment ratios are yet to be discussed and confirmed.

Lou would welcome participation by Japan, the United States and Europe. The banks' global agenda will be set at a later date, after the Asian framework is settled.