The Ministry of Finance, using the Bank of Japan as its agent, stepped into the market on March 18 after G7 nations agreed on a rare joint intervention after the yen hit a post World War II dollar high of 76.25 to the greenback.

The moves by Japanese, US, eurozone, Canadian and British monetary authorities -- their first concerted action in a decade -- pushed the yen down from highs hit after the March 11 earthquake and tsunami.

The currency traded at 82.92 to the dollar Thursday.

The joint action demonstrated international sympathy for Japan's plight, as volatile currency movements threaten its crucial export sector.

A strong yen makes goods more expensive overseas and erodes companies' repatriated profits.

Japan intervened unilaterally in September 2010 to weaken the unit in a move that drew criticism from some corners. It has threatened it would intervene again to weaken the yen if it viewed the currency's movements as volatile.

Dealers said the yen's post-earthquake surge was helped by speculators betting on an influx of capital by Japanese companies to aid reconstruction efforts.