BEIJING, May 29 (Reuters) - Nickel prices gained more than 2 percent to a 3-year high in Shanghai on Tuesday, and rose also in London as trading resumed after a UK public holiday on Monday. Long positions held by brokerages on the Shanghai Futures Exchange's (ShFE) July nickel contract increased by around 5,000 lots to 117,911 lots on Monday, according to exchange data. Malcolm Freeman, CEO of Kingdom Futures, noted that nickel had made the most progress among London Metal Exchange (LME) base metals also, but was "once again meeting the overhead resistance at the $15,000 level." "It will take today for the markets to realign as all participants are active once again before a clearer picture emerges and prices gain a sense of direction," Freeman added. FUNDAMENTALS * NICKEL: The most-traded July nickel contract on the ShFE rose as much as 2.7 percent to 112,800 yuan ($17,558.37) a tonne, its highest since May 2015. Shanghai nickel is up by around 7.9 percent so far this month. * NICKEL: Three-month nickel on the London Metal Exchange was up 1.3 percent at $14,975 a tonne. * COPPER: London copper edged down 0.2 percent to $6,870.50 a tonne as the dollar index gained, making metals more expensive for holders of other currencies. Shanghai copper edged up 0.4 percent. * SHFE: Major state copper and aluminium producers were among the companies that traded almost half a billion yuan of metal on the ShFE's new physical trading platform on its debut on Monday, the exchange said. * ALUMINIUM: China's state-owned Chinalco is set to close the gap on privately run China Hongqiao Group, the world's top aluminium producer, after sealing a deal with the Yunnan government that gives it access to more smelting capacity. * LITHIUM: Australian lithium miner Galaxy Resources Ltd GXY.AX agreed on Tuesday to sell a package of mining tenements in Argentina to South Korean steelmaker POSCO 005490.KS for $280 million.