Some Bank of Japan policymakers thought in December that the central bank's key interest rate of 0.1 percent was its "lowest possible level," indicating reluctance to cut borrowing costs further, a summary of the minutes of the Policy Board's meeting showed Tuesday.

During the meeting Dec. 18 and 19, the eight-member Policy Board voted to cut the benchmark short-term rate from 0.3 percent to 0.1 percent. This followed the cut it made in October, when the overnight call rate was 0.5 percent.

"Some members expressed the view that 0.1 percent was the lowest possible level it could have without impairing the proper functioning of the market mechanism," the summary said.