New York, April 26 (Bloomberg) -- The yen sank to a one-week low against the dollarafter the International Monetary Fund's chief economist, Michael Mussa, said a furtherdrop in the currency would not be a cause for concern. The losses picked up steam after Japan's new finance minister, Masajuro Shiokawa,said foreign-exchange rates should be left to the currency market and not manipulatedby the government. Japan's currency fell to 123.50 per dollar, from 122.11 yesterday, after Shiokawa saidcurrency prices ``should be totally left to the market.'' He made his remarks at a pressconference after the first meeting of the cabinet of Japan's new prime minister, JunichiroKoizumi. ``The perception is that if dollar-yen were left to the market, we'd be up to 135-140'' yenper dollar, said Grant Wilson, a trader at Mellon Financial Corp. in Pittsburgh. Mussa, speaking at an IMF briefing, said ``modest further depreciation of the yen shouldnot be of concern,'' given the need to revive growth in Japan. With a marked fall in theyen, ``toward or even beyond the low point of the yen in June of 1998,'' then some officialstatement of concern ``would be useful,'' he said. The yen sank to an eight-year low of 147.66 per dollar in August 1998. Japan's currency has rebounded about 3 percent since the start of the month, aftersinking to a 30-month low of 126.84 on April 2, on the view that Japanese officials did notwant the currency to decline further and might buy yen to support it. The comments today also pushed the yen lower against the euro, driving it to 111.18 pereuro from 109.68 yesterday.