BEIJING, June 7 (Reuters) - London copper prices rose to a 2018 high on Thursday, gaining ground for a sixth session on concerns over disruption at the Escondida mine in Chile. Three-month copper on the London Metal Exchange hit $7,287 a tonne, its highest since Dec. 29, 2017, and was trading at $7,276 at 0707 GMT. It is up 6.3 percent so far this month. Investors "continue to fret about potential supply-side disruptions" after union leaders at Escondida, which is operated by BHP, submitted wage demands, sparking fears of a possible strike, ANZ wrote in a note. A weaker dollar index, which makes dollar-denominated metals cheaper for holders of other currencies, also lent support to prices. FUNDAMENTALS * SHFE COPPER: The most-traded July copper contract on the Shanghai Futures Exchange rose for a fifth straight session, ending 2.2 percent higher at 53,930 yuan ($8,440.41) a tonne, its highest close since Feb. 27. * PREMIUMS: China copper premiums CU-BPCIF-SHMET have held steady at $77.5 a tonne over the past month, indicating there has been no heightened shortage of physical metal in the world's top copper consumer. * POSITIONS: Long positions among futures brokerages in the July ShFE copper contract increased by 2,220 lots on Thursday, while short positions were up by 1,262 lots for July and 12,277 lots for August. * ALUMINIUM: Shanghai aluminium ended up 1.9 percent at 15,020 yuan a tonne, its highest close since April 23. London aluminium recovered from an early dip to trade 0.2 percent higher. * LME CONTRACTS: The London Metal Exchange (LME) plans to launch around 15 new contracts next January, including cash-settled cobalt and hot-rolled coil steel contracts, an executive said on Wednesday. * SCOTIA: Canada's Bank of Nova Scotia (Scotiabank) is limiting lending by its ScotiaMocatta metals unit as it embarks on a radical restructuring likely to halve the size of the business, sources familiar with the matter said. * CHILE: Chile's finance minister on Wednesday described as "imprudent" the appointment by lithium miner SQM of its former Chairman Julio Ponce as a strategic adviser, in light of an agreement with the state that he distance himself from the firm.