SHANGHAI, Dec 7 (Reuters) - China stocks fell on Monday, dragged down by financials, due to worries over heightened Sino-U.S. tensions, although upbeat trade data narrowed losses. ** The blue-chip CSI300 index fell 0.9%, to 5,022.24, while the Shanghai Composite Index declined 0.8% to 3,416.60. ** The tech-heavy start-up board ChiNext slipped 0.2%, while STAR50 index added 0.1%. ** Falling the most, the CSI300 banks index dropped 2.2%, while the CSI300 financials index slid 2%. ** The United States is preparing to impose sanctions on at least a dozen Chinese officials over their alleged role in Beijing’s disqualification of elected opposition legislators in Hong Kong, according to three sources, including a U.S. official, familiar with the matter. ** The news came after the United States on Thursday added China’s top chipmaker, SMIC, and oil giant CNOOC to a blacklist of alleged Chinese military companies. ** China’s senior diplomat Wang Yi said on Monday he hoped and believed that U.S. policy on China could eventually “return to objectivity and rationality”. ** Losses were contained after customs data showed that China’s exports in November rose 21.1% from a year earlier, after 11.4% growth in October, while imports grew 4.5% last month from a 4.7% expansion in October. ** A brisk factory recovery in China from coronavirus shutdowns earlier this year has far outpaced reopenings seen in major trading partners, many of which are still struggling with outbreaks. ** Around the region, MSCI’s Asia ex-Japan stock index was firmer by 0.83%, while Japan’s Nikkei index closed down 0.76%. ** At 07:08 GMT, the yuan was quoted at 6.5411 per U.S. dollar, 0.17% weaker than the previous close of 6.53. ** As of 07:09 GMT, China’s A-shares were trading at a premium of 45.21% over Hong Kong-listed H-shares. (Reporting by Shanghai Newsroom; editing by Richard Pullin)