BEIJING—The president of China's giant sovereign-wealth fund warned Japan against using its neighbors as a "garbage bin" by deliberately devaluing the yen, joining growing international griping about a potential currency war.

In unusually strong language, Gao Xiqing, president of China Investment Corp., echoed alarms from Latin America to Europe that the new Japanese government is aiming to boost its exports at other countries' expense via a weaker currency—allegations often leveled at China itself by the U.S. and...