The head of Japan's largest business lobby says the Japanese yen may further lose value, after the currency slid to the 148 level against the dollar.

Chairman Tokura Masakazu of the Japan Business Federation, or Keidanren, told reporters on Monday that the United States is doing everything it can to cool off its red-hot economy. Against that backdrop, he said, speculators are betting on the interest-rate gap between Japan and the US to widen.

Tokura said the Bank of Japan may be able to adjust interest rates by a small margin, but not enough to satisfy speculators. He added that it's "unrealistic" to try to control exchange rates through such interest-rate adjustments.

He suggested that Japan can take advantage of the weakening yen, such as drawing more foreign tourists.