MELBOURNE, April 13 (Reuters) - London aluminium slipped on Friday but was on track for its biggest weekly gain on record after the United States imposed sanctions on Russia's UC Rusal, the world's second biggest producer of the metal. FUNDAMENTALS * London Metal Exchange aluminium fell by 1.5 percent to $2,290.50, trimming gains for the week that were still approaching 14 percent. Prices topped out at $2,325 a tonne on Thursday which was a six-year high. * COPPER: LME copper edged up by 0.1 percent to $6,830.50 a tonne by 0203 GMT, adding to 1.9 percent drop from the previous session. Prices have support at the 200-day moving average of $6,743. Shanghai Futures Exchange copper eased by 0.7 percent to 50,520 yuan ($8,031.29) a tonne. * CHINA TRADE: China's commerce ministry said on Thursday trade negotiations with the United States would be impossible as Washington's attempts at dialogue were not sincere, and vowed to retaliate if U.S. President Donald Trump escalates current tensions. * US TRADE: President Donald Trump said on Thursday that the trade "negotiations" between Washington and Beijing were going well, conflicting with Chinese official statements on the dispute. * RUSAL: U.S. sanctions on Russian businesses and individuals are hitting companies including aluminium giant Rusal controlled by tycoon Oleg Deripaska and triggering responses across markets. * US ALUMINIUM STOCKS: Almost all the aluminium in the United States was removed from Comex warehouses this week, as consumers scramble to stock up ahead of the sanctions on the world' second biggest aluminium maker, Rusal, that is expected to crimp supply. Stocks tumbled by about 44,000 tonnes to 11,168 tonnes. AL-TTLTTDY-STX * SCRAMBLE: The rush for stocks was also reflected in time spreads on the LME with soaring prices for cash aluminium against the benchmark three-month contract. Cash aluminium traded $52 against three months, the highest in more than a decade. CMAL0-3 * POLLUTION: In what could potentially help U.S. aluminium makers boost production more quickly, U.S. President Donald Trump on Thursday ordered the Environmental Protection Agency to speed up its decision-making on air quality permitting to make it easier for manufacturers to expand and open new plants.