BEIJING, Oct 22 (Reuters) - London copper prices rose for a second session in early Asian trade on Monday, extending a rally fuelled by a pledge from China's central bank that it would support firms with liquidity problems. FUNDAMENTALS: * LME COPPER: Three-month copper on the London Metal Exchange edged up 0.3 percent to $6,236.50 a tonne as of 0210 GMT, extending a 1 percent jump from the previous session. * SHFE COPPER: The most-traded December copper contract on the Shanghai Futures Exchange climbed by 0.8 percent to 50,390 yuan ($7,270) a tonne. * OTHER METALS: Nickel was the biggest gainer, tracking gains in China's ferrous complex to rise 1.7 percent in London and 1.9 percent in Shanghai. Zinc slipped by as much as 1.8 percent in Shanghai after the ShFE on Friday reported a 23.3 percent jump in zinc inventories. * NICKEL: The bulk of nickel moving out of London Metal Exchange-approved warehouses in Asia is showing up in hidden facilities in Europe, analysts said, denting a bullish scenario of potential shortages. * HKEX: A Shenzhen-based commodity exchange controlled by Hong Kong Exchanges and Clearing unexpectedly began spot trading on Friday, giving the HKEX much-coveted access to mainland China's market. * LITHIUM: Canada's Nutrien, whose attempt to sell its stake in Chilean lithium miner SQM to China's Tianqi Lithium has been stalled by a row about competitive risks, vowed to "protect its interests" in an interview with a Chilean newspaper published on Sunday.