China has surpassed Japan to become the world's largest holder of foreign exchange reserves, according to the state-owned China Business News.As of February 28, China held $853.7 billion, as compared to Japan's $850.2 billion according to the China Business News. The figure has yet to be confirmed by the central bank. Increasing reserves may heighten pressure from the U.S. to relax controls on the yuan, which was revaluated at 2.1% in July and is managed against a basket of currencies. Senators are currently drafting legislation that would put punitive tariffs on Chinese imports. Official reserves will be released at the end of the first quarter, according to a central bank official.