* SSEC -1.2%, CSI300 -1.6%, HSI -2.4%

* Consumer firms drag after surging in the previous session

* Tencent slumps, pulls Hang Seng lower

SHANGHAI, Jan 26 (Reuters) - China shares fell on Tuesday, with blue chips pulling back from a 13-year high touched in the previous session, as investors locked in profits in high-flying consumer firms, and as investor concerns continued to simmer over Sino-U.S. relations.

** At the midday break, the Shanghai Composite index was down 1.2% at 3,580.83 points. ** China's blue-chip CSI300 index was down 1.61%, with the consumer staples sector down 0.75% and the consumer discretionary index down 3.02%. ** Consumer staple and discretionary firms had lifted the CSI300 index to its highest level since January 2008 on Monday. ** China-U.S. relations continue to weigh on sentiment. China said on Tuesday it will conduct military exercises in the South China Sea this week, just days after Beijing bristled at a U.S. aircraft carrier group's entry into the disputed waters. ** U.S. President Joe Biden wants to approach relations with Beijing with "patience," the White House said on Monday. ** Meanwhile, index provider MSCI Inc said it will delete securities of five Chinese companies from some indexes as of the close on Jan. 27 in the absence of any guidance. ** CGN Power Co slumped 5.95%, China Shipbuilding Industry fell 1.2% and Inspur International dropped 2.23%. China National Nuclear Power and China National Chem posted small gains. ** Chinese H-shares listed in Hong Kong fell 2.18% to 11,700.24, while the Hang Seng Index was down 2.4% at 29,434.08. ** Tencent Holdings Ltd dropped 6.39% a day after the surging nearly 11% amid heavy buying by mainland investors. ** The smaller Shenzhen index was down 1.6%, the start-up board ChiNext Composite index was weaker by 2.39% and Shanghai's tech-focused STAR50 index was down 1.31%. ** The yuan was quoted at 6.4713 per U.S. dollar, 0.13% firmer than the previous close of 6.4798. (Reporting by Andrew Galbraith; editing by Uttaresh.V)