China's Finance Ministry said on Saturday that the U.K. and Switzerland had been formally accepted as founding members of the Asian Infrastructure Investment Bank (AIIB), a day after Brazil accepted China's invitation to join the AIIB.
China's AIIB has been seen as a challenge to the World Bank and Asian Development Bank, and a significant step for China's global influence.
China's Finance Ministry said that Austria had also applied to join, and has submitted its documents to China.
"We should push forward with the creation of a regional hub for financial co-operation," said Chinese President Xi Jinping on Saturday at a forum in Boao on the southern Chinese island of Hainan.
China should "strengthen pragmatic cooperation in monetary stability, investment, financing, credit rating and other fields," Xi added.
Brazil, China's top trading partner, said on Friday it would join the AIIB and that there were no conditions set for joining.
Read More How Europe and US stumbled into spat over China-led bank
"Brazil is very interested in participating in this initiative," the office of President Dilma Rousseff said in a short statement on Friday.
AIIB's founding members have increased to 30, according to China's Finance Ministry statement.
The United States had warned against the new institution but its European allies Britain, France, Germany and Italy announced this month they would join the bank, leading the U.S. administration to reassess its stance.