The new head of the nation¡¯s main banking lobby is warning the Bank of Japan against deepening negative interest rates, signaling that such a move could spur risky investment and put further pressure on lenders¡¯ profits.

¡°It will be a quite difficult option to take,¡± Makoto Takashima, chairman of the Japanese Bankers Association, said in an interview. ¡°Simply speaking, that would cause policy side effects to further grow.¡±

Speculation for more BOJ easing has resurfaced as the economy weakens and central banks around the world pivot away from policy tightening.