* Copper rangebound ahead of key China data * Alcoa cuts aluminium demand forecast on China slowdown * Hopes for more China stimulus limits losses By Carrie Ho SHANGHAI, Oct 10 (Reuters) - London copper fell for a fourth straight session on Wednesday as worries about the global economy and a bleak demand outlook offset hopes for pro-growth policies from top metals consumer China. Aluminium dropped more than 1 percent, weighed down by the cautious mood and after top U.S. aluminium producer Alcoa Inc cut its global demand growth forecast this year due to the slowdown in China. Having climbed about 8-11 percent in September on stimulus measures from central banks, prices for aluminium and copper have turned down recently with traders keenly awaiting data from China for hints on the country's demand for commodities. Three-month copper on the London Metal Exchange, ticked down 0.3 percent to $8,125 per tonne by 0712 GMT. Prices have moved less than $50 in the session, indicating caution ahead of China data, including September trade figures, third-quarter gross domestic product and industrial output, over the coming week. "London copper is unlikely to breach its technical support at $8,000-$8,100 ahead of the China data. If it did, there is no telling how much prices can plunge from those levels," said a Shanghai-based copper buyer. Weak demand from China, which is still battling high inventories, has been weighing on copper prices. Its appetite for imports is also anaemic as overseas shipments are more expensive than domestic supply, Mirae Assets Securities said in a note on Wednesday. In a sign of tepid demand, copper inventories monitored by the Shanghai Futures Exchange are up 74 percent from the start of the year at 162,547 tonnes. Spot copper is also trading at a discount of around 120 yuan to the ShFE front month contract. The most active January copper contract on the Shanghai Futures Exchange fell 0.6 percent to close at 58,860 yuan ($9,400) per tonne. But losses are expected to be limited by fresh signs of pro-growth policies by China to stabilise the world's second-largest economy. Chinese state-backed media said major insurance firms had boosted their combined stock holdings by more than 10 billion yuan ($1.6 billion) over the last three trading days and will continue to support blue chip stocks and stock markets. Another paper said China is likely to offer incentives to spur vehicle sales in rural areas to boost consumption and support a slowing economy. China's annual economic growth probably slowed for a seventh straight quarter in the July-September period to the weakest level since the depths of the global financial crisis, a Reuters poll showed, reinforcing the case for further policy stimulus. LME aluminium dropped to a one-month low of $2,019.75 a tonne after Alcoa slashed its global demand growth forecast for this year. "We've lowered our demand projection for this year to 6 percent, down 1 percentage point from the 7 percent that we saw before. Main driver for this is China," Alcoa Chairman and Chief Executive Officer Klaus Kleinfeld said in a conference call with analysts on Tuesday. Base metals prices at 0712 GMT Metal Last Change Pct Move YTD pct chg LME Cu 8125.00 -20.00 -0.25 6.91 SHFE CU FUT JAN3 58860 -370 -0.62 5.81 LME Alum 2025.00 -29.00 -1.41 0.25 SHFE AL FUT JAN3 15585 -80 -0.51 -1.61 HG COPPER DEC2 370.25 -1.55 -0.42 7.76 LME Zinc 1993.75 -13.25 -0.66 8.06 SHFE ZN FUT JAN3 15410 -165 -1.06 4.16 LME Nickel 17824.00 -106.00 -0.59 -4.74 LME Lead 2233.00 -18.50 -0.82 9.73 SHFE PB FUT 15910 -120 -0.75 4.05 LME Tin 21650.00 -175.00 -0.80 12.76 LME/Shanghai arb 910 Shanghai and COMEX contracts show most active months ^ LME 3-m copper in yuan, including 17 pct VAT, minus SHFE third month

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