Japan intervened in currency markets Thursday, driving down the yen by more than 3 percent in an effort to shore up its export sector.

Finance Minister Yoshihiko Noda said Japan’s recovery from its twin disasters was threatened by the rise of the yen, which was approaching a post-World War Two high. That record was set immediately after the March 11 earthquake and tsunami.

Noda did not comment on the size of the intervention, which Japan made after consulting with its international partners. But news reports said Japan’s treasury sold off 1 trillion yen, valued at $12.6 billion, to flood the market and drive down the price.

The Bank of Japan also acted by expanding a fund used to buy up financial assets. The effect was to inject more money into the system, helping bring down the yen’s value.

Late Thursday, the yen was trading at about 79 and three quarters to the dollar compared to a high of 76.29 on Monday.

A high yen hurts Japan’s export-oriented economy by making its products more expensive in foreign markets. The rise in the yen against the dollar was blamed on international concerns about weakness in the U.S. economy.

At a news conference, Noda described the recent movements in the yen as “one-sided” and “excessive.”