* SSEC -0.3 pct, CSI300 -0.6 pct, HSI -0.4 pct
* Shanghai Composite touches lowest point since Feb. 2016
* Hang Seng hits lowest level since July 2017
SHANGHAI, Sept 12 (Reuters) - China stocks fell on Wednesday morning, dragging the Shanghai Composite and the blue-chip CSI300 indexes down to new multi-year lows, as worries over escalation in the U.S.-China trade war hit investor sentiment, with China seeking WTO sanctions.
** At the midday break, the Shanghai Composite index was down 8.91 points or 0.33 percent at 2,655.89. It fell as low as 2,647.17 in the morning session, its lowest point since Feb. 29, 2016.
** China's blue-chip CSI300 index was down 0.61 percent at midday, having earlier touched its lowest point since Aug. 8, 2016.
** The CSI300 financial sector sub-index was lower by 0.4 percent, the consumer staples sector down 1.69 percent, the real estate index down 0.76 percent and the healthcare sub-index down 2.26 percent.
** Chinese H-shares listed in Hong Kong fell 0.95 percent to 10,234.64, while the Hang Seng Index was down 0.4 percent at 26,317.89. The Hang Seng earlier touched its lowest intraday level since July 12, 2017.
** China told the World Trade Organization (WTO) on Tuesday it wanted to impose $7 billion a year in sanctions on the United States in retaliation for Washington's non-compliance with a ruling in a dispute over U.S. dumping duties.
** Chinese Vice Premier Hu Chunhua said on Wednesday countries should "categorically reject" protectionism in trade.
** The smaller Shenzhen index was down 0.15 percent and the start-up board ChiNext Composite index was weaker by 0.18 percent.
** Around the region, MSCI's Asia ex-Japan stock index was weaker by 0.34 percent while Japan's Nikkei index was down 0.39 percent.
** The yuan was quoted at 6.8757 per U.S. dollar, 0.06 percent weaker than the previous close of 6.8719.
** The largest percentage gainers in the main Shanghai Composite index were Will Semiconductor Co Ltd Shanghai, up 10.01 percent, followed by Guizhou Guihang Automotive Components Co Ltd, gaining 10 percent and Zhejiang Rongsheng Environmental Protection Paper Joint Stock Co Ltd, up by 10 percent.
** The largest percentage losses in the Shanghai index were Harbin Gong Da High-Tech Enterprise Development Co Ltd , down 4.92 percent, followed by Dynagreen Environmental Protection Group Co Ltd, losing 4.71 percent and Yifeng Pharmacy Chain Co Ltd, down by 4.46 percent.
** So far this year, the Shanghai stock index is down 19.42 percent, while China's H-share index is down 11.8 percent. Shanghai stocks have declined 2.22 percent this month.
** The top gainers among H-shares were Great Wall Motor Co Ltd , up 5.17 percent, followed by China Resources Land Ltd , gaining 1.6 percent and CNOOC Ltd, up by 1 percent.
** The three biggest H-shares percentage decliners were CSPC Pharmaceutical Group Ltd, which has fallen 6.92 percent, China Pacific Insurance Group Co Ltd, down 2.4 percent and Huaneng Power International Inc, which was 2.2 percent lower.
** About 5.11 billion shares have traded so far on the Shanghai exchange, roughly 43.2 percent of the market's 30-day moving average of 11.83 billion shares a day. The volume traded was 9.99 billion as of the last full trading day.
** As of 04:16 GMT, China's A-shares were trading at a premium of 21.06 percent over the Hong Kong-listed H-shares.
** The Shanghai stock index is below its 50-day moving average and below its 200-day moving average.
** The price-to-earnings ratio of the Shanghai index was 11.21 as of the last full trading day, while the dividend yield was 2.8 percent.
** So far this week, the market capitalisation of the Shanghai stock index has fallen by 1.34 percent to 28.39 trillion yuan.
** In Hong Kong, the sub-index of the Hang Seng index tracking energy shares dipped 0.1 percent while the IT sector rose 0.2 percent. The top gainer on Hang Seng was MTR Corp Ltd, up 2.77 percent, while the biggest loser was Sino Biopharmaceutical Ltd, which was down 10.16 percent.
(Reporting by Andrew Galbraith; Editing by Sunil Nair)