TOKYO 鈥 Japanese policy makers on Monday continued efforts to tame sharp yen falls, including through two straight market days of suspected intervention, but ultimately failed to prop up the currency against persistent dollar strength.

The yen鈥檚 sell-off is hurting the world鈥檚 third-largest economy by driving already surging import bills and challenges the Bank of Japan鈥檚 (BoJ) commitment to ultra-low rates in the face of rapid global monetary tightening to combat rampant inflation.

The Japanese currency jumped 4 yen to 145.28 per dollar in early Asia trade on Monday, suggesting authorities had stepped in for a second straight day after a similar move by Tokyo on Friday.

鈥淲e won鈥檛 comment,鈥 Masato Kanda, vice finance minister for international affairs, told reporters at the Ministry of Finance, when asked if they intervened again on Monday.

鈥淲e are monitoring the market 24/7 while taking appropriate responses. We鈥檒l continue to do so from now on as well,鈥 said Mr. Kanda, who oversees Japan鈥檚 exchange-rate policy.

However, the yen failed to cling to early gains and briefly hit a low of 149.70 per dollar, as markets continued to focus on the widening divergence between the BoJ鈥檚 ultra-easy monetary policy and steady rate hike plans by the US Federal Reserve. It last stood around 148.80.

鈥淚n the past crises involving British pound and Italy鈥檚 lira, authorities have ended up failing to defend their currencies. Likewise, Japan鈥檚 stealth intervention only has limited effects,鈥 said Daisaku Ueno, chief foreign exchange (FX) strategist at Mitsubishi UFJ Morgan Stanley Securities.

鈥淪trength in the dollar is the biggest factor behind the weak yen. If the United States shows signs of its rate hikes peaking out and even cutting interest rates, the yen would stop weakening even without intervention.鈥

BOJ鈥檚 BIND
The yen鈥檚 plight puts the BoJ under the spotlight as it meets for a two-day rate meeting ending on Friday, when it is widely expected to maintain ultra-loose monetary policy.

With inflation relatively modest and the economy unable to move into a faster gear, the central bank is wary of raising rates and risk triggering a recession.

鈥淚t鈥檚 extremely undesirable鈥 that Japan鈥檚 real wages, adjusted for inflation continue to fall, BoJ Governor Haruhiko Kuroda told parliament on Monday.

鈥淚t鈥檚 desirable for inflation to stably achieve our 2% target accompanied by wage rises,鈥 Mr. Kuroda said, stressing the need to keep supporting the economy with ultra-low rates.

The Fed, which meets the following week, is widely expected to hike rates again as it focuses on fighting red-hot inflation.

The widening US-Japanese rate differential is likely to keep downward pressure on the yen, which has fallen more than 20% against the dollar this year.

Japanese authorities confirmed that they stepped into the market when it intervened on Sept. 22, spending 2.8 trillion yen ($18.80 billion) to prop up the yen for the first time since 1998.

Since then, authorities have remained silent on whether they made any further attempts to support the currency including on Friday, when Tokyo likely conducted stealth intervention.

Finance Minister Shunichi Suzuki repeated that excessive currency moves were undesirable.

鈥淲e absolutely cannot tolerate excessive moves in the foreign exchange market based on speculation,鈥 he told reporters at the finance ministry. 鈥淲e will respond appropriately to excess volatility,鈥 he said, a view echoed by Prime Minister Fumio Kishida in parliament later on Monday. 鈥 Reuters