China's foreign exchange reserves expanded slightly to 3.1072 trillion U.S. dollars at the end of August, official data showed Saturday. 

The amount increased by 3.5 billion U.S. dollars, or 0.1 percent from the end of July, according to the State Administration of Foreign Exchange (SAFE). 

Wang Chunying, a spokesperson for the SAFE, attributed the rise to exchange rate fluctuations and changes in asset prices. 

"Factors including the global economic growth, trade situation and geopolitics led to the modest rise in the U.S. dollar index as well as the increase in bond prices of major countries," Wang said. 

Despite mounting external uncertainties, the Chinese economy has maintained overall stability and posted stable growth with an improved economic structure, Wang said, citing the overall balance of international payments and the firm growth of forex reserves. 

Wang expected the foreign exchange market to remain stable in the long term amid fluctuations, supported by the solid foundations and the continuous reform and opening-up.