BEIJING, April 25 (Reuters) - London aluminium dropped as much as 1.4 percent on Wednesday, retreating for a fifth straight session, as the softening of the U.S. sanctions on Russian producer United Company Rusal continued to weigh on prices. The metal has now slipped by around 13 percent from a high of $2,534.50 on April 23, the day the United States gave American customers of Rusal more time to comply with sanctions. While traders watch for more news on Rusal, Norsk Hydro is scheduled to release earnings on Wednesday, "so the market awaits potential updates regarding the situation at Alunorte," broker Marex Spectron said in a note, referring to the company's 51 percent-owned alumina plant in Brazil. Alunorte, the world's biggest alumina refinery, was ordered to shut half of its output in late February amid a probe into allegations the site contaminated local water supplies. Norsk Hydro has warned this could impact its aluminium production in Norway. FUNDAMENTALS * LME ALUMINIUM: Three-month aluminium on the London Metal Exchange was down 1.2 percent at $2,200 a tonne, as of 0458 GMT, having closed down 3 percent on Tuesday. Earlier in the session, it touched a low of $2,196. * SHFE ALUMINIUM: The most-traded June aluminium contract on the Shanghai Futures Exchange was up 0.3 percent at 14,465 yuan ($2,294.28) a tonne by the mid-session interval, rising for the first time in four days. * RUSSIA: Russia's En+ Group, owned by recently sanctioned businessman Oleg Deripaska, said its chief executive officer and its chief financial officer resigned on Tuesday, with replacements appointed to both posts. * NICKEL: London nickel climbed 1 percent to $14,130 a tonne, trading higher for the first time in five days after falling 8.4 percent from April 19 as fears of sanctions spreading eased. * FREEPORT: Shares of Freeport-McMoRan Inc fell more than 14 percent on Tuesday after the miner revealed onerous environmental demands from Indonesia's government that could delay a new contract for its massive Grasberg copper mine. * CUBA: Cuba forecasts nickel plus cobalt sulfide production will exceed 50,000 tonnes this year even as prices rise, the head of the country’s state monopoly Cubaniquel was quoted by local media as stating on Tuesday.