TOKYO, April 9 -- A senior economist said in Tokyo Thursday that Japanshould join China-proposed Asian Infrastructure Investment Bank (AIIB) as soon as possible for the benefits of Japan itself and other member countries.

Kiyoyuki Seguchi, research director at the Canon Institute for Global Studies, believed that benefits to be brought by AIIB are great especially in infrastructure area.

However, "If Japan does not participate in the AIIB, the country's companies will be in a disadvantageous position when competing for infrastructure contracts in the rest of Asia," Seguchi, who used to be the chief representative of the Representative Office of Bank of Japan in Beijing, said at a press conference Thursday.

With the development of AIIB, more demerits of Japan's out of it will gradually show up. "Japan's influence in an important channel directly involved with regional economic cooperation in the Asia-Pacific will decrease," said Seguchi.

He believed that AIIB's operations will be improved with Japan' s participation as the country has rich operating experience in other similar organizations such as the Asian Development Bank ( ADB).

Talking about AIIB and ADB, Seguchi said they could go in good direction together. "The AIIB's smooth development, which may serve ADB as a competing force, would turn ADB an even better organization."

Cooperation between China and Japan will bring huge benefits to Asia, and Asia's development will also bring opportunities for Japan's investment, machinery and construction fields, he noted.