The New York Federal Reserve Bank confirmed that it intervened in currency markets on Friday for the first time in more than a decade.
The disclosure came a day after the Group of Seven major industrialized nations pledged in a statement to join in a coordinated effort to weaken the Japanese yen. The yen has surged in the last week to post-war record levels following the Japanese earthquake and tsunami.
A spokesman at the New York Fed, which operates as the agent of the U.S. Treasury in currency operations, confirmed that it had intervened. The last time the U.S. government intervened in currency markets was the fall of 2000 when it sold dollars and bought euros to bolster the fledgling European currency.
The spokesman refused to provide any details on the amounts of the intervention or what currencies were involved.
A stronger yen threatened to deal another blow to the fragile Japanese economy by depressing the country's exports.
In morning trading in New York on Friday, a dollar was buying 81.30 yen, up from 79.05 yen late Thursday and moving off its postwar low of 76.32 yen hit on Wednesday. Before the earthquake struck, one dollar bought 83.02 yen.