New Zealand has formally become a member of the Asian Infrastructure Investment Bank (AIIB), Finance Minister Bill English said Tuesday.

New Zealand's ratification would contribute to the AIIB reaching the 50-percent threshold of the needed for the AIIB to establish operations, English said in a statement.

The move followed the passage of the International Financial Agreement Amendment Act in the New Zealand Parliament in November.

New Zealand was the ninth country to formally become a founding member.

"New Zealand was the first developed Western nation to join negotiations to set up the AIIB, and our membership will enhance our already strong economic, trade and investment links with the Asian region," English said.

"Through our role in establishing the AIIB, we have been able to ensure it has strong governance, environmental and social policies, and transparency, so we have good reason to expect it to deliver efficiently and effectively," he said.

"New Zealand is benefiting from the rapid and sustained economic development across Asia. For this to continue, the region needs to address constraints posed by infrastructure bottlenecks."

The AIIB would have around 100 billion US dollars of initial capital to promote sustainable development in the region.

New Zealand's paid in capital will be around 125 million NZ dollars (83.05 million US dollars), paid over five years.

AIIB investments would include improving transportation links, providing sanitation and clean drinking water, and supporting cleaner and more sustainable energy.

The bank was expected to begin operations in January 2016.