BEIJING, Feb 15 (Reuters) - London copper prices slipped on Friday after China's factory-gate price growth missed expectations and as investors awaited the outcome of Sino-U.S. trade talks in Beijing. China's producer price inflation slowed for a seventh straight month in January to its weakest pace since September 2016, raising concerns the world's top copper consumer may see the return of deflation as domestic demand cools. Copper is on course for a 1.5 percent drop this week, which would be its steepest weekly fall since the week ended Dec. 22. Key catalysts for a price rebound would be progress in the trade talks and signs of economic recovery in China, Helen Lau, an analyst at Argonaut Securities in Hong Kong, said in a note. China's January copper import numbers, released on Thursday, reflected a "rather encouraging outlook in copper demand, especially as inventory in the domestic market is winding down," she added. FUNDAMENTALS * LME COPPER: Three-month copper on the London Metal Exchange fell 0.3 percent to $6,118.50 a tonne, as of 0355 GMT, having climbed in the previous two sessions. The most-traded April copper contract on the Shanghai Futures Exchange was flat at 48,330 yuan ($7,132.42) a tonne. * TRADE: The top two U.S. negotiators in trade talks with China will meet on Friday with Chinese President Xi Jinping, but there has been no decision to extend a March 1 U.S. deadline for a deal, White House economic adviser Larry Kudlow said. * VIBE: "The vibe in Beijing is good," Kudlow told Fox News Channel but his upbeat assessment contrasted with reports from two people familiar with the talks, who said progress has been difficult on the thorniest issues. * NICKEL: The metal used to make stainless steel fell 0.6 percent in London and was on course to shed 3.5 percent over the week, the most since November, as a rally driven by fears Vale's tailings dam disaster in Brazil would affect its nickel production faded. ShFE nickel lost 1.8 percent. * NICKEL: Further easing supply fears, Australian ferronickel miner South32 has agreed a four-year contract with two unions at its Cerro Matoso mine in Colombia, avoiding a strike over pay and other benefits.