Japan spent 7.15 trillion yen on currency-market intervention in January, marking a new single-month record, Finance Ministry data showed Friday.

With Japanese monetary authorities struggling to keep the yen from rising against the dollar, the amount used between Dec. 27 and Jan. 28 easily surpassed the previous monthly record — September's 5.11 trillion yen.

Japan used more than 20 trillion yen to intervene in the currency market in 2003, an almost three-fold increase from the previous yearly record — the 7.64 trillion yen spent in 1999.