PARIS ¨C Japan stands ready to act against excessive foreign exchange volatility at any time, while ensuring that any yen-buying, dollar-selling intervention is conducted in a way that avoids pushing up U.S. Treasury yields, officials said on Monday.

¡°As we ?have stated previously, we will respond appropriately at any time if ?necessary¡± against ?excessive currency volatility, Finance Minister Satsuki Katayama told reporters ?after the first day of a Group of Seven finance leaders¡¯ two-day gathering.

She told her counterparts at the G7 meeting that fluctuations in crude ?oil prices continue to spill over into foreign exchange rates and government bond yields.

Tokyo ?may have spent nearly ?10 trillion ($63 billion) since launching its latest round of yen-buying intervention starting April 30, central bank ?data indicates, marking Japan¡¯s first foray ?into the market in almost two years.

After rising to around ?155 per dollar in early May, ?the yen has since ?surrendered more than half of its gains, coming ?close to the ?160 mark that is seen as the Japanese ?authorities¡¯ ?line in the sand for intervention.

Katayama declined to comment on whether Japan had intervened, adding that the issue was not raised during the G7 meeting. ¡°That said, volatility itself was discussed, and its causes include developments ?in the Middle East as well as speculative behavior,¡± she said.

Rising U.S. Treasury yields have fueled market speculation that Washington may become sensitive to large-scale yen-buying, dollar-selling intervention by Japan, which draws on its roughly $1.4 trillion foreign exchange reserves.

Because ?the ?bulk of those reserves is held in U.S. Treasuries, ?intervention could, in theory, involve selling such assets.

However, a Finance Ministry official said ?on Monday that Japan maintains ample liquidity within its reserves, including cash deposits as well as a steady flow of maturing assets and interest income.

Selling Treasurys to fund intervention could push up U.S. yields and, ?in turn, strengthen the dollar ¡ª an outcome that would be counterproductive, the official said.

With that in mind, authorities manage reserves to ensure they can act effectively while minimizing unintended market impacts, the official added.