Japanese officials stepped up their expressions of concern about a soaring yen as the currency's renewed strength threatened to undermine the government's Abenomics program for reviving the economy.

With the yen trading near a 15-month high against the dollar, concern is growing that this will reduce the competitiveness of Japanese exports and also cut the value of profits brought home from overseas operations. A weaker outlook for earnings risks undermining the country's annual round of wage talks, currently underway. And by making imports cheaper, the trend also hurts the Bank of Japan's campaign to spur inflation.

"As the G-7 and the G-20 have agreed, abrupt market movements are not desirable," Finance Minister Taro Aso said Friday in Tokyo. "There have been very rough movements in the FX market. We will continue to watch FX markets with a sense of urgency and will respond appropriately when necessary."