BEIJING, Dec 21 (Reuters) - Copper edged higher on Friday, supported by concerns over lower mine output and a report by an industry study group showing a widening supply deficit. The metal has declined 1.8 percent so far this week in London, in what would be its fourth straight weekly fall, and lost almost 17 percent in 2018, heading for its worst year since 2015 on fears the U.S.-China trade row will hurt demand. "We think markets have focused too much on the demand side and ignored slower-than-expected mine output growth," Helen Lau, a metals and mining analyst with Argonaut Securities, wrote in a note. "The outlook for global (copper) mine supply for 4Q18 and FY19 is quite dull," she said, adding that worker protests at Codelco's' Chuquicamata mine in Chile may further constrain output next year. FUNDAMENTALS * LME COPPER: Three-month copper on the London Metal Exchange rose by 0.3 percent a tonne to $6,020 a tonne as of 0511 GMT, reversing Thursday's 0.3 percent dip. * SHFE COPPER: The most-traded February copper contract on the Shanghai Futures Exchange nudged up 0.2 percent to 48,280 yuan ($7,008.48) a tonne by the end of the morning session. * COPPER: The global world refined copper market showed a 168,000 tonne deficit in September, compared with a 43,000 tonne deficit in August, the International Copper Study Group (ICSG) said in its latest monthly bulletin. * CONTRACTS: Chilean state miner Codelco has agreed to sell France's Nexans, China's Minmetals and U.S.-based Southwire 50,000 to 100,000 tonnes of copper each from 2019 to 2021 in rolling deals known as "evergreens", sources close to the matter said. * OTHER METALS: Most other base metals made modest gains in quiet pre-holiday trade, with nickel adding 0.5 percent in London and Shanghai aluminium climbing 0.7 percent. * ALUMINIUM: Representatives from China's biggest aluminium producers will hold a meeting on Friday in the southern region of Guangxi to discuss slumping demand and low prices, said three sources familiar with the matter.