HONG KONG, Jan 8(Reuters) - China and Hong Kong stocks fell on Wednesday, led by declines in the chip and consumption sectors, as geopolitical tensions and economic uncertainties kept sentiment subdued. ** At the midday break, China's blue-chip CSI300 index .CSI300 was down 1.5%, and the Shanghai Composite index .SSEC weakened 1.46% to 3,182.48 points. ** In Hong Kong, the benchmark Hang Seng Index dropped 1.6%, extending its decline to a third consecutive day and reaching its lowest point since late September. ** Leading the decline onshore, shares of semiconductor firms .CSI931865 tumbled 3.3%, giving up most of the gains made on Tuesday after the U.S. Defense Department expanded the list of firms allegedly aiding Beijing's military. ** Shares of chipmaker Semiconductor Manufacturing International Corporation 688981.SS shed 4.7% to a nearly three-week low and peer Hua Hong Semiconductor 688347.SS lost 4.3%. ** China's consumption sector .CSICS fell 1.3% despite Beijing's latest measures to expand scope of consumer trade-ins. ** "A combination of an escalation in U.S.-China tensions, looming tariff uncertainty stemming from the incoming U.S. administration, and likely muted policy actions from China ahead of the March NPC suggests that Chinese equities will likely go through a volatile period until policy delivery materializes," analysts at Goldman Sachs said in a note on Wednesday. ** Around the region, MSCI's Asia ex-Japan stock index .MIAPJ0000PUS was weaker by 0.60% while Japan's Nikkei index .N225 was down 0.13%.

** Chinese ADRs .HXC fell 0.2% overnight.

** The yuan CNY=CFXS was quoted at 7.3316 per U.S. dollar, 0.04% weaker than the previous close of 7.3284.

(Reporting by Jiaxing Li; Editing by Sherry Jacob-Phillips)

((jiaxing.li@thomsonreuters.com))