The nation's top financial regulator said regional banks "should not blame the Bank of Japan" for their woes, urging them to explore ways to survive ultralow interest rates.

"They should not just sit and wait for the BOJ to change its policy. Will everything be alright if it seeks exit and normalizes interest rates? I don't think so," Toshihide Endo, commissioner of the Financial Services Agency, said in an interview Wednesday.

The comments come as many of the roughly 100 regional banks grapple with diminishing returns from their traditional lending business, hit by a low interest rate environment amid the BOJ's ultraloose monetary policy.