(Reuters) – Japan’s key economic ministers kept investors wary of currency market intervention, warning that authorities were watching with a “strong sense of urgency” as the yen slid closer to the 150 per dollar level on Monday, its weakest in nearly a year.

Last September, Japanese authorities conducted their first intervention in 24 years, when the yen weakened past 145 per dollar, and speculation has mounted that they will step in again with the yen under constant pressure due to a yawning yield gap against the dollar.

“As I said before, we are closely watching market moves with a strong sense of urgency,” Finance Minister Shunichi Suzuki told Reuters on Monday.

The finance minister has jurisdiction over currency intervention, but he declined to comment on whether it was a possibility at this point.

Chief Cabinet Secretary Hirokazu Matsuno echoed his stance, telling reporters that the government would continue to monitor currency moves with “a high sense of urgency”.

He also repeated that it is important that the currency market moves in a stable manner reflecting fundamentals.

Japanese officials in a recent few weeks have said they would not rule out any options on intervention, but they have yet to utter the tell-tale phrases they used before unleashing intervention last year.

Back then they spoke of being ready to take “decisive steps” and were “deeply concerned” on the yen’s weakening.

Investors believe an increase in the speed of the yen’s depreciation would be more likely to trigger intervention than a move past any specific level.

A fundamental reason for the yen’s weakness, however, is the divergent monetary policies being conducted by the Bank of Japan and the U.S. Federal Reserve.

While there is market speculation that the Fed could raise interest rates yet again before the year end, the Japanese central bank appears hesitant about shifting away from the ultra-loose policy it has pursued for years in a effort to conclusively break the Japanese economy free of deflation.