A Bank of Japan Policy Board member urged banks Thursday to downsize in number and asset holdings to become more profitable, pointing to structural factors, rather than the BOJ's easing policy, as being behind the deterioration in their profitability.

In a speech to business leaders in the city of Oita, Yutaka Harada brushed off criticism that low interest rates, part of the BOJ's stimulus efforts, have eaten into the banks' lending margins, saying the financial institutions in Japan suffer from the structural problem of "accumulating more deposits than they can lend."

"Banks in Japan do not seem to be trying to reduce deposits, but instead are relying on riskier lending or investment," he said.