Nov 12 (Reuters) - The US Treasury bought Japanese yen in the July-to-September quarter, but the Federal Reserve did not intervene of its own accord in foreign exchange markets in the same period, the Federal Reserve Bank of New York said on Thursday.
The New York Fed's quarterly report on currency market operations detailed interventions executed on behalf of the Treasury this summer to stem a sharp weakening of the yen.
The purchase was the first US yen-buying intervention since 1998, and the report shows Washington acted alongside Tokyo to support the Japanese currency.
On July 30, press reports emerged that the New York Fed had requested "rate checks" on the dollar-yen rate. The New York Fed report said the checks were made "solely on behalf of the US Treasury," with the New York Fed acting as the government's fiscal agent. The yen rose 2.3% against the dollar that day.
The New York Fed said it bought 79.4 billion yen ($497.37 million) in the spot market on July 31, selling euros from the Exchange Stabilization Fund.
The New York Fed made the purchase "to counter what the US Treasury viewed as disorderly moves in the Japanese yen," its report said.
Japan's Ministry of Finance acted in coordination, intervening "in the amount of 15.4 trillion yen" during the quarter to counter what it saw as excessive volatility and disorderly yen moves, the New York Fed added.
The yen recovered quickly. Between July 30 and August 3, the dollar-yen rate fell "from around 164 yen per dollar to around 155 yen per dollar," the report said.
After the joint operation, Treasury Secretary Scott Bessent said the US would do "whatever it takes" to support Japan's effort to stabilize the yen.
($1 = 159.6400 yen)
(Reporting by Mrinmay Dey in Mexico City; Editing by Chris Reese and Jamie Freed)