BEIJING, July 17 (Xinhua) -- Investment on U.S. treasury bills is safe so far, as there are no better alternatives amid the global financial market instability, experts told Xinhua Friday after China substantially increased the holding in May.

    China, with the world's largest foreign exchange reserves, or 2.13 trillion U.S. dollars, bought 38 billion U.S. dollars worth of the bills in May, the highest monthly increase in nine months. The holding was 801.5 billion U.S. dollars, according to the U.S. Treasury Department's website late Thursday.

    "It is within expectation as the U.S. dollar's role in the international monetary system is irreplaceable in the short-run," said Ding Zhijie, deputy director of the School of Banking and Finance of the University of International Business and Economics.

    China added 80.6 billion U.S. dollars of foreign reserves in May, according to the figure released by the People's Bank of China. It means 47 percent of the new reserves were used to buy the U.S. treasury bills.

    Ding said there are no better investment alternatives as the global financial market was volatile in May. The U.S. economy posted a better performance than other major economies at the time.

    Chinese officials have aired concerns that the falling U.S. dollar could hurt the value of China's massive holding of U.S. dollar assets.

    The U.S. Treasury Secretary Timothy Geithner said that China's U.S. dollar assets are safe in his visit to China in June.

    Chen Bingcai, researcher with the China National School of Administration, said China has been cutting long-term bills and buying more short-term bills to improve investment structure.

    He said China does not have to worry too much about the issue alone, since it does no good for the U.S. economy if it relies too much on capital from China.

    Wang Tao, a researcher with the China Minsheng Bank, said China still needs to diversify its investment mix to avert risks.

    He said China should use the huge stockpile to buy strategic resources, and advanced technologies.

Special Report:  Global Financial Crisis