* Upbeat U.S. data bolsters case for curbing Fed stimulus * Copper stocks reverse trend, rise on LME and in Shanghai * All base metals except lead hit three-week lows By Maytaal Angel LONDON, Aug 30 (Reuters) - Copper hit a three-week low on Friday on expectations that upbeat U.S. data would bolster the case for the Federal Reserve to start withdrawing stimulus next month, though the metal looked set for its biggest monthly gain in nearly a year. Copper has rebounded more than 4 percent in August on signs of a stabilising global economy, in particular top consumer China, but the market faces headwinds going into September. U.S. President Barack Obama is said to be willing to proceed with limited military action against Syria even without specific promises of allied support, notably from Britain. The political uncertainty is denting appetite for risky assets such as copper. Meanwhile, the case for Fed tapering of monetary stimulus was bolstered further on Thursday by positive U.S. growth and jobless claims data, keeping the dollar index steady near a four-week high. A stronger U.S. currency makes dollar-priced metals costlier for European and other non-U.S. investors. "We've had some encouraging economic data especially out of China, but our feeling is that copper has peaked and will now edge lower. We see looming surplus building in the second half and the Fed tapering will probably see some speculative selling of commodities," said Robin Bhar, analyst at Societe Generale. Three-month copper on the London Metal Exchange was down 0.30 percent at $7,131.50 a tonne by 0954 GMT, having earlier edged lower to $7,122.50, the lowest since Aug. 8. The metal is on track to close the week down more than 3 percent, the biggest weekly loss since mid-June. Aluminium, zinc, tin and nickel all followed copper to three-week lows. Lead hit its lowest in 2-1/2 weeks. Weighing on copper, data earlier showed stocks of that metal in Shanghai Futures Exchange warehouses rose 0.3 percent from last Friday, interrupting a downtrend in place since mid-June that had taken stocks to one-year lows. Daily LME data showed a large 10,325-tonne rise in copper stocks to 588,000, interrupting a downtrend in place since late June that had taken stocks to their lowest since March. On the upside for copper, however, China's factory activity in August may have expanded at the fastest pace in three months, a Reuters poll showed, adding to evidence that the world's second-largest economy may be stabilising. China accounts for about 40 percent of global copper demand. "Going into the fourth quarter we usually see a bit of restocking demand from China. We're not expecting a huge recovery in the copper market, but prices could come back up to $7,500," said commodity analyst Natalie Rampono of ANZ in Melbourne. In industry news, Ecuador's state mining company Enami EP will create a joint venture with the world's top copper producer, Codelco, to explore the Llurimagua copper reserves in the north of Ecuador, the head of Enami said. Metal prices at 0959 GMT Comex copper in cents/lb, LME prices in $/T and SHFE prices in yuan/T Metal Last Change Pct Move End 2012 Ytd Pct move COMEX Cu 3.24 -0.01 -0.37 365.25 -99.11 LME Alum 1814.50 -20.50 -1.12 2073.00 -12.47 LME Cu 7127.25 -25.75 -0.36 7931.00 -10.13 LME Lead 2160.25 -134.75 -5.87 2330.00 -7.29 LME Nickel 13856.00 -219.00 -1.56 17060.00 -18.78 LME Tin 21110.00 -295.00 -1.38 23400.00 -9.79 LME Zinc 1910.00 -25.00 -1.29 2080.00 -8.17 SHFE Alu 14270.00 -110.00 -0.76 15435.00 -7.55 SHFE Cu* 52080.00 -290.00 -0.55 57690.00 -9.72 SHFE Zin 14820.00 -115.00 -0.77 15625.00 -5.15 ** Benchmark month for COMEX copper * 3rd contract month for SHFE AL, CU and ZN SHFE ZN began trading on 26/3/07

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