BEIJING, March 6 (Reuters) - Shanghai zinc prices fell to their lowest since December on Tuesday, tracking a decline on the London Metal Exchange (LME) after LME warehouse inventories rose and on-warrant zinc stocks - those not earmarked for delivery - nearly doubled. The metal, used to galvanise steel, is also coming under pressure from looming U.S. tariffs on steel imports. FUNDAMENTALS * SHFE ZINC: The most traded April zinc contract on the Shanghai Futures Exchange was down 2.5 percent at 25,335 yuan ($3,998.07) a tonne at 0206 GMT, on course for its biggest daily drop since October. It earlier touched 25,210 yuan a tonne, its lowest since Dec. 15. * LME ZINC: Zinc in London was up 0.1 percent at $3,298.50 a tonne after hitting a 2018 low in the previous session. Stocks of zinc in LME warehouses MZN-STOCKS jumped by 59 percent on Monday to 209,050 tonnes, while on-warrant levels nearly doubled to 162,825 tonnes. * LME COPPER: Three-month copper on the London Metal Exchange was up 0.4 percent ar $6,936 on a weaker dollar, extending a 0.2 percent gain in the previous session. A weaker greenback makes metals cheaper for holders of other currencies and can support prices * SHFE COPPER: The most-traded April copper contract on the Shanghai Futures Exchange edged up 0.1 percent to 52,180 yuan a tonne. * TRUMP: U.S. President Donald Trump faced growing pressure on Monday from political and diplomatic allies as well as U.S. companies urging him to pull back from proposed steel and aluminum tariffs, although he said he would stick to his guns. * INDONESIA: Indonesia's President Joko Widodo has instructed his administration to complete negotiations over the purchase of a majority stake in Freeport-McMoRan Inc's local unit by the end of April, a cabinet minister said on Monday. * COBALT: Australia's Celsius Resources, which has made Namibia's first cobalt discovery, is aiming to start production from the remote mine in 2020, the company's managing director said. * For the top stories in metals and other news, click or MARKETS NEWS * Asian shares regained some ground on Tuesday after U.S. President Donald Trump faced growing pressure from political allies to pull back from proposed steel and aluminium tariffs, easing investor worries about an imminent trade war. PRICES BASE METALS PRICES 0206 GMT Three month LME copper 6936 Most active ShFE copper 52180 Three month LME aluminium 2143.5 Most active ShFE aluminium 14355 Three month LME zinc 3297.5 Most active ShFE zinc 25335 Three month LME lead 2415 Most active ShFE lead 18510 Three month LME nickel 13465 Most active ShFE nickel 102290 Three month LME tin 21540 Most active ShFE tin 147070 BASE METALS ARBITRAGE LME/SHFE COPPER LMESHFCUc3 1166.41 LME/SHFE ALUMINIUM LMESHFALc3 -1416.07 LME/SHFE ZINC LMESHFZNc3 584.09 LME/SHFE LEAD LMESHFPBc3 38.59 LME/SHFE NICKEL LMESHFNIc3 1710.92 ($1 = 6.3368 Chinese yuan renminbi) (Reporting by Tom Daly; editing by Richard Pullin)