The yen strengthened past the 157 level against the dollar on Wednesday, supported by a series of government warnings on the currency's exchange rate and quarter-end capital flows.

In early Asian trading, the yen rose as much as 0.6% to 156.38, making it the best performer among G10 currencies.

Japan's top currency official, Atsushi Mimura, said on Monday that the Japanese Prime Minister and Finance Minister have recently joined the United States in sending a "very clear" signal regarding the currency's depreciation.

"The market appears to be gradually embracing the view that policy may shift toward being more supportive of the yen," said Moh Siong Sim, a strategist at OCBC Bank. "The yen has remained firm since Trump expressed concern about yen weakness earlier this week."

Speculation is building that the Bank of Japan may raise interest rates again as early as next month, after the central bank hiked by 25 basis points to 1.25% earlier this month.

Since Tokyo and Washington conducted their first joint intervention in 15 years in July to support the yen, the currency has appreciated by roughly 3.6% this quarter.

Shinya Koike, manager of the global market trading department at Sumitomo Mitsui Trust Bank, said quarter-end capital flows may also be one of the reasons behind the yen's rise.