The nation's customs-cleared trade surplus for calendar 1997 grew for the first time in five years, increasing 48.5 percent from the year before to 10.01 trillion yen, the Finance Ministry said Thursday.The rise means the surplus has returned to the levels of the early 1990s, when trade friction with the U.S. and other countries was rampant. Provisional figures showed that exports increased 13.9 percent to 50.95 trillion yen, while imports logged a smaller year-on-year growth of 7.8 percent to 40.94 trillion yen.Chief Cabinet Secretary Kanezo Muraoka downplayed the rise, attempting to allay concerns in other nations over the trend. "Thanks to the yen's decline, the trade surplus is rising," he said. "There are various fears regarding the financial system. The yen's weakness is gradually being rectified and the rise of the trade surplus is unlikely to last. "I think this is a temporary phenomenon," he addedThe exchange rate for the year was put at 120.41 yen to the dollar compared with 108.33 yen in 1996. Ministry officials acknowledged that the surplus would probably continue to grow for the time being, but said they still believe that structural changes in the Japanese economy would prevent the figure from surging significantly.The rise in exports was helped by a 29 percent increase in automobile exports and 20 percent growth for office equipment such as personal computers. On the import side, Japan saw a 15.7 percent rise in oil imports and a 22.9 percent increase in liquid natural gas imports.On a regional basis, the trade balance with the U.S. rose for the first time in three years, registering a 41.7 percent rise to 5.02 trillion yen. Exports to the U.S. grew 16.3 percent to 14.17 trillion yen, overshadowing the 5.9 percent rise in imports to 9.14 trillion yen. While exports were buoyed by increases of 23.6 percent for autos and 19.3 percent for precision optical instruments, auto imports from the U.S. fell 31.9 percent compared with the previous year.With the European Union, Japan's surplus grew for the first time since 1992, registering a 67.3 percent rise to 2.48 trillion yen. The trade surplus with Asia marked the first rise in two years, increasing 14.4 percent to 6.36 trillion yen.Ministry officials said that while trade with some Asian nations has been falling in recent months, it is unclear to what extent the currency and financial turmoil that has gripped the region since last summer has affected the figures.