The Bank of Japan must immediately end its negative interest rate policy as it has allowed companies to delay efforts to boost productivity by keeping borrowing costs ultralow, ruling party heavyweight Shigeru Ishiba said in an interview Monday.

"It's an extreme policy that shouldn't exist in the first place," Ishiba said of negative interest rates, adding that ultralow rates can be justified only in times of crisis.

When asked whether he meant the BOJ should end negative rates as soon as possible, Ishiba said: "Yes, I believe so."