LONDON, Dec 28 (Reuters) – Copper prices jumped to a four-year peak on Thursday as funds bet on strong demand in top consumer China and supply disruptions in top producer Chile leaving the market short of the metal used widely in power and construction. Benchmark copper on the London Metal Exchange was up 0.3 percent at $7,264 a tonne at around 1215 GMT from an earlier $7,312.5, its highest since January 2014. It is up more than 30 percent so far this year. „Funds are on a buying spree, but the timing and strength is surprising,“ said Quantitative Commodity Research consultant Peter Fertig. „Fundamentals are good. China is a growing economy, it will need more copper. The risk of strikes in Latin America due to labour negotiations is looming.“ China accounts for about half of global copper demand estimated at around 23.5 million tonnes. That is why a surge in its imports to 329,168 tonnes in November, up 19 percent from the same period a year ago, triggered a buying frenzy this week. Analysts estimate China’s copper demand growth could be as high as three percent in 2018 from around two percent this year. They will be watching surveys of purchasing managers in China’s manufacturing sector and industrial production growth, which are typically used as lead indicators for copper demand. „Heading into next year, a case can be made for a relatively higher trading range for copper compared to what we saw in 2017,“ INTL FCStone analyst Edward Meir said in a note. Meir expects the copper market to see a 130,000 tonne deficit next year after a shortfall of 95,000 tonnes this year. „One variable that should help the market next year is the fact that there will be a series of key labor negotiations that could potentially impact a substantial amount of metal.“ Given copper’s 70 percent gains since hitting a 6-1/2 year low of $4,318 in January 2016, expectations are for unions to be more militant, particularly given the concessions they made when prices were tumbling. Analysts at Citi say there are over 30 labour contracts, covering around five million tonnes of mine supply, due to expire next year, most of them in Chile and Peru. „The largest identifiable potential issue concerns the Escondida contract due June, 2018, given the 2 month strike earlier this year,“ they said. „To reflect elevated supply risks over the next 12 months we assume a 6.0 percent disruption allowance for 2018 or 1.26 million tonnes vs 5.2 percent average since the financial crisis or 970,000 tonnes.“ Also helping copper is the lower U.S. currency, down 10 percent since the start of this year against a basket of other major currencies, making dollar-priced commodities cheaper for holders of other currencies. This relationship is used by funds which trade using buy and sell signals generated by numerical models.