BEIJING, Jan. 27 (Xinhua) -- China's foreign exchange watchdog said Thursday that the surplus of Chinese banks' foreign exchange purchases to sales in client transactions increased 51 percent through 2010 to stand at 397.7 billion U.S. dollars at year-end.

China' s institutional and individual clients sold 1.33 trillion U.S. dollars in foreign exchange to banks in 2010 while purchasing 932.7 billion U.S. dollars, said the State Administration of Foreign Exchange (SAFE) in an online statement.

In 2009, the annual surplus fell 42 percent to 263.5 billion U.S. dollars, according to SAFE's data released in March 2010.

The statement noted the figures did not include banks' own forex transactions and interbank transactions.

The forex surplus in December 2010 totaled 51.5 billion U.S. dollars, as clients sold 146.2 billion U.S. dollars of foreign exchange, up 13 percent from November, while purchasing 94.7 billion U.S. dollars, up 12 percent, it said.

Chinese banks received 1.89 trillion U.S. dollars for their clients in overseas business in 2010 and paid 1.59 trillion U.S. dollars to overseas business, it added.

The SAFE only began releasing monthly and quarterly data on bank foreign exchange transactions in 2010.