China shares flat as concerns over Sino-U.S. relations loom

China stocks were largely unchanged on Tuesday, as investors reviewed their positions after recent gains triggered by optimism over fresh policies to support the economy, though concerns about deteriorating Sino-U.S. relations lingered.

** At the midday break, the Shanghai Composite index was down 0.11% at 2,912.09 points.

** China's blue-chip CSI300 index was down 0.04%, as of 0415 GMT, with its financial sector sub-index climbing 0.51%, the consumer staples sector down 0.19%, the real estate index up 0.98% and the healthcare sub-index down 1.14%.

** Chinese H-shares listed in Hong Kong fell 0.22% to 9,812.26, while the Hang Seng Index was up 0.38% at 23,823.03.

** The smaller Shenzhen index was down 0.14% and the start-up board ChiNext Composite index was weaker by 1.02%.

** The China government ordered state-owned firms to halt large-scale U.S. soybean purchases, raising the specter of damaging trade disagreements between Washington and Beijing.

** Shares in China's Hainan-based listed firms including Hainan Haide Industry Co Ltd, Hainan Dadonghai Tourism Centre (Holdings) and Huawen Media Group all surge by 10% daily trade limit in morning tradings, as Beijing vows to further open up the southern island.

** Hong Kong shares extended gains, from the biggest rally in more than two months hit in the previous session after U.S. President Donald Trump's measured response to China's national security law in Hong Kong.

** Around the region, MSCI's Asia ex-Japan stock index was firmer by 0.44%, while Japan's Nikkei index was up 1.22%.

** The yuan was quoted at 7.12 per U.S. dollar, 0.13% firmer than the previous close of 7.129.