The Bank of Japan broke its monthly record for purchases of long-term Japanese government bonds in January. It has been on a massive bond-buying spree to curb a rise in interest rates to stimulate the economy.

The BOJ says it bought 23.69 trillion yen or about 182 billion dollars of long-term JGBs in the month. That exceeds the previous record set last June.

Investors speculated the central bank may further tweak its monetary policy following an adjustment in December that allowed the yield of the benchmark 10-year issue to move in a wider band.

That view prompted sell-offs. The bank responded by buying a large amount of bonds to keep the 10-year yield below its upper limit of half a percent.

The central bank already possessed more than half of Japan's outstanding long-term bonds at the end of last September.