The Bank of Japan sold an estimated 3.1 trillion yen in dollar-supporting interventions in the last two weeks, making it the largest round of such interventions on record, according to market analysts.
The central bank has been actively wading into both the Tokyo and overseas foreign exchange markets in an effort to shore up the dollar following the Sept. 11 terrorist attacks in the United States.
The previous record for a round of BOJ yen-selling intervention was 3 trillion yen in the April-June period of 1999.
The BOJ has shown fierce determination to prop up the dollar, which traded at 120 yen levels before the terrorist attacks but later plunged briefly to the 115 yen level on worries about the impact of the attacks on the U.S. economy.
The BOJ first intervened in the Tokyo market on Sept. 17 after the dollar fell to the 116 yen level. It has since continued its dollar-supporting efforts in both Tokyo and London.
On Thursday, the Federal Reserve Bank of New York also stepped into the market on the BOJ's behalf, helping to push the dollar up to the 120 yen level at one point in New York trading.
The BOJ move is aimed at helping improve the competitive position of Japanese exports, a major driving force for an economic recovery.