Japan's food self-sufficiency rate on a calorific intake basis slipped to 39 percent in fiscal 2010, down 1 percentage point from a year earlier, dropping beneath the 40 percent line for the first time in four years, the farm ministry said Thursday.

The Agriculture, Forestry and Fisheries Ministry blamed the decline mainly on falls in domestic production of wheat and beet sugar. The ratio skidded for the second consecutive year.

Although the government has sought to achieve the goal of hiking the rate to 50 percent in fiscal 2020, the latest data show that Japan is facing growing difficulties in clearing the goal.

Japan has one of the lowest food self-sufficiency rates among major industrialized countries, farm ministry's estimates show.

On a value basis, the self-sufficiency rate dropped by 1 point to 69 percent, a decrease for the first time in two years, the ministry said. The drop is attributable to poor production of milk stemming from the summer heat.

The food self-sufficiency rate refers to the ratio of domestically consumed food that is supplied by domestic production.

Japan's food self-sufficiency rate stood at 73 percent in fiscal 1965 but has since followed a downward path in tandem with a trend of declining rice consumption and has remained at around 40 percent since the mid-1990s.