TOKYO, Jan 30 (Reuters) - Japan's exports of refined copper rose 26 percent in December from a year earlier, aided by a 40 percent jump in cathode sales to China, Ministry of Finance data showed on Monday. Exports of refined copper, which includes cathode and billet, totaled 39,309 tonnes, though they were down from the previous month's 46,278 tonnes. A robust expansion in exports to China, the world's top consumer of the metal, slowed from the previous month's 100 percent jump, but volume stayed at a high level due to improved arbitrage, buying at London Metal Exchange copper prices and selling at Shanghai prices <0#SCF:> CU-1-CCNMM. China's refined copper imports rose 18.3 percent in December on the month to a record high also due to increased use of copper for financing purposes, according to the General Administration of Customs data announced this month. Demand for copper, found in industrial products ranging from cars to computer chips, is seen as a gauge of economic activity. China, Taiwan and Indonesia are the key export markets for Japanese copper. Following are refined copper and copper cathode exports (in tonnes): Type Dec 11 Nov 11 Dec 10 Jan-Dec 11 Jan-Dec 10 Refined* 39,309 46,278 31,180 610,358 528,372 Cathode only 36,046 44,532 28,761 402,114 491,313 * Includes cathode copper

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