Japan's merchandise trade surplus grew 107.9 percent in August from a year earlier to 644.1 billion yen, the sixth straight month of year-on-year growth, according to a preliminary report released Wednesday by the Finance Ministry.

Strong demand for Japanese goods in Europe and throughout the rest of Asia supported the increase in the customs-cleared merchandise trade surplus -- exports minus imports.

Exports rose 6.2 percent from the previous year to 4.07 trillion yen, up for the fifth consecutive month, while imports fell 2.7 percent to 3.42 trillion yen, marking the first decrease in two months.