Japan shares weighed down by weak China factory activity report

TOKYO, Jan 23 (Reuters) - The Nikkei stock average reversed early gains to end 0.8 percent lower on Thursday after a survey showed manufacturing activity in China, one of Japan's top trading partners, contracted in January for the first time in six months. The Nikkei ended 125.07 points lower at 15,695.89, breaking below its five-day moving average of 15,737.79. Before the release of the disappointing flash Markit/HSBC Purchasing Managers' Index survey, the benchmark had risen as high a