Hatoyama's government is "currently discussing how far it can curtail (such expenses) in cooperation with the United States," the Japanese leader told reporters in the evening, adding the amount of such budgetary allocations have already been declining in recent years.

Under the agreements with Washington, Tokyo covers part of the expenses for U.S. troops for staying in Japan, such as construction of their residences and utility costs, and pays salaries of Japanese employees working at U.S. bases in Japan. The spending is often called the "sympathy" budget.

In the fiscal 2009 budget, 192.8 billion yen has been earmarked for such expenses. The figure comes below the 200 billion yen line for the first time since fiscal 1992.

During a House of Representatives plenary session earlier in the day, Hatoyama said, "A comprehensive review" is necessary to make Japan's fiscal burden a "more efficient and effective" one.

But Hatoyama, leader of the ruling Democratic Party of Japan, also expressed concern that if the expenses are reduced considerably, it could have a substantial impact on the economy in Okinawa Prefecture, Japan's southernmost prefecture which hosts the bulk of the U.S. military presence in the country.