BEIJING, July 15 (Reuters) - China's economy is facing increasing external uncertainties and many domestic difficulties and challenges in the second half, a spokesperson for the National Bureau of Statistics said on Monday.

China's GDP growth of 5% in the first half was "hard won" as businesses face relatively large pressures and key sectors face many risks, the spokesperson said in a statement published on the bureau's website.

The spokesperson also said China's economic growth in the second quarter was affected by short-term factors such as extreme weather and flooding. (Reporting by Beijing newsroom and Kevin Yao; Editing by Kim Coghill)