Adopting or deepening negative interest rates is an unlikely option for many central banks including in Japan, former Bank of Japan policymaker Sayuri Shirai has said, particularly when they need the help of commercial banks to pump funds to firms hit by the coronavirus pandemic.

The BOJ and the European Central Bank have negative interest rates in place to stimulate their economies, though the policy has been criticized as eroding financial institutions' profits and discouraging them from lending.

Markets have also recently priced in a small chance the U.S. Federal Reserve might resort to a negative rate policy, which its Chair Jerome Powell brushed off Wednesday.