* CSI300 -0.65%, SSEC flat

* Shanghai tightening COVID measures to eliminate infections

* Yuan touches new 18-month low

* Hong Kong markets closed for holiday

SHANGHAI, May 9 (Reuters) - Chinese blue-chip shares fell on Monday as growing concerns over the economic impact of COVID-19 lockdowns weighed on investor sentiment, with new trade data reflecting soft demand.

** At the midday break, China's blue-chip CSI300 index was down 0.65% at 3,883.51 points and the Shanghai Composite index was flat at 3,001.62 points.

** The CSI300 financial sector sub-index fell 0.53% and the consumer staples sector slipped 1.7%.

** Liquor makers were among the biggest losers on Monday on concerns over the widening impact of COVID-19 curbs, with a sub-index tracking the sector down 2.61%

** Index heavyweight Kweichow Moutai Co Ltd fell 2.36%, making it the biggest drag on the CSI300.

** Chinese automakers fell after an industry group estimated that sales in April dropped 48% year-on-year, as zero COVID-19 policies shut factories, limited traffic to showrooms and put the brakes on spending.

** The CSI Automobiles Index fell 1.36%.

** New customs data released Monday showed coal imports dropping in the January-April period as COVID-19 control measures dampened demand.

** China's biggest city is tightening its lockdown in a fresh push to eliminate infections outside quarantined areas by late this month, people familiar with the matter told Reuters.

** Markets in Hong Kong are closed on Monday for a public holiday.

** The smaller Shenzhen index was up 0.41%, the start-up board ChiNext Composite index was weaker by 0.35% and Shanghai's tech-focused STAR50 index was up 0.52%.

** Around the region, MSCI's Asia ex-Japan stock index was 1.22% weaker while Japan's Nikkei index was down 2.09%.

** Around midday in China, the yuan was quoted at 6.7073 per U.S. dollar, having touched a new 18-month low earlier in the session.

** So far this year, the Shanghai stock index is down 17.5% and the CSI300 has fallen 21.4%. Shanghai stocks have declined 1.49% this month. (Reporting by Andrew Galbraith; editing by Uttaresh.V)