BEIJING, Feb 1 (Reuters) - London base metals prices fell on Friday after a closely watched private survey showed that factory activity in China, the world's top metals consumer, shrank by the most in almost three years last month. The Caixin/Markit Manufacturing Purchasing Managers' Index (PMI) for January fell to 48.3 - its worst reading since February 2016 - from 49.7 in December. The survey came a day after China's official manufacturing PMI showed a second straight monthly contraction but was higher than consensus, lifting industrial metal prices along with dovish comments from the U.S. Federal Reserve on interest rates. "Unlike the state statistics, the Caixin Manufacturing PMI is derived exclusively from a survey of 430 private industrial companies which is exactly the sector that the government has been trying support for several months," John Browning, managing director of brokerage Bands Financial, wrote in a note. FUNDAMENTALS * COPPER: Three-month copper on the London Metal Exchange was down 0.7 percent at $6,128.50 a tonne as of 0503 GMT, having hit a seven-week high in the previous session. The metal widely used in manufacturing and construction is heading for a weekly rise of 1.2 percent. * SHFE: The most traded March copper contract on the Shanghai Futures Exchange was down 0.1 percent at 47,990 yuan ($7,132.88) a tonne. * HOLIDAYS: The ShFE will close after Friday's afternoon session for China's Lunar New Year holiday, re-opening on Feb. 11. * COPPER: Top copper miner Codelco said it had struck a contract deal with the union of supervisors at its Gabriela Mistral mine in northern Chile, averting the threat of a strike. * TRADE TALKS: U.S. President Donald Trump said he will meet with China's Xi Jinping soon to try to seal a comprehensive trade deal, citing substantial progress in two days of high-level talks. * ZINC: The most-traded ShFE zinc contract surged 2.5 percent to a nine-month high of 22,460 yuan a tonne before easing to 22,190 yuan. LME zinc, which hit a seven-month high on Thursday amid tight stocks, was down 0.2 percent. * ALUMINIUM: Aluminium Corp of China Ltd, known as Chalco, has stopped production at an aluminium smelting plant in eastern China's Shandong province, citing high electricity costs.