China stocks end lower, but post biggest monthly gain in nearly 4 years

* SSEC -0.4 pct, CSI300 -0.25 pct

* SSEC gains 13.8 pct in Feb, CSI300 up 14.6 pct Biggest monthly rises since April 2015

* Factory activity slows for third month in Feb

SHANGHAI, Feb 28 (Reuters) - Chinese shares ended lower on Thursday on concerns about Sino-U.S. trade and slowing growth, but the country’s main stock indexes posted their biggest monthly gains in nearly four years on investor hopes for government stimulus and policy support. ** At the close, the Shanghai Composite index was down 0.44 percent at 2,940.95. The index ended February with a 13.8 percent rise, its biggest monthly gain since April 2015. ** The blue-chip CSI300 index finished down 0.25 percent, but posted its biggest monthly gain since April 2015, rising 14.6 percent. ** The smaller Shenzhen index ended up 0.35 percent and the start-up board ChiNext Composite index was higher by 1.004 percent. ** Factory activity in China contracted for the third straight month in February, and export orders fell to the lowest level since the global financial crisis, underscoring concerns over a slowdown in the world’s second-largest economy. ** U.S. Trade Representative Robert Lighthizer on Wednesday cautioned that much work was still needed to nail down a U.S.-China trade agreement, including working out how it will be enforced, and that the United States would need to maintain the threat of tariffs on Chinese goods for years even if Washington and Beijing strike a deal to end a costly tariff war. ** But highlighting official concern about supporting the country’s financial markets, a central bank official said on Thursday that China would strengthen real-time monitoring of its stock, bond and foreign exchange markets to guard against risks. ** Around the region, MSCI’s Asia ex-Japan stock index was weaker by 0.61 percent, while Japan’s Nikkei index closed down 0.79 percent. ** At 07:15 GMT, the yuan was quoted at 6.6828 per U.S. dollar, 0.04 percent firmer than the previous close of 6.6855. ** The largest percentage gainers on the main Shanghai Composite index were Henan Yinge Industrial Investment Co Ltd, up 10.15 percent, followed by Hualing Xingma Automobile Group Co Ltd, gaining 10.12 percent, and Shanghai Shenqi Pharmaceutical Investment Management Co Ltd, up by 10.09 percent. ** The largest percentage losers on the Shanghai index were Shanghai AJ Group Co Ltd, down 10.02 percent, followed by Shanghai Shibei Hi-Tech Co Ltd, losing 10.02 percent, and Anxin Trust Co Ltd, down by 10.01 percent. ** So far this year, the Shanghai stock index is up 17.9 percent and the CSI300 has risen 21.9 percent, while China’s H-share index listed in Hong Kong is up 12.2 percent. ** About 35.02 billion shares were traded on the Shanghai exchange, roughly 161.0 percent of the market’s 30-day moving average of 21.76 billion shares a day. The volume in the previous trading session was 47.50 billion. (Reporting by Andrew Galbraith; Editing by Subhranshu Sahu)