* Indonesia may impose tax or quota on ore exports * Nickel stocks hit lowest since February 2009 * Coming up: U.S. job data, 1230 GMT; Obama speech 2300 GMT By Silvia Antonioli LONDON, Sept 8 (Reuters) - Copper steadied on Thursday as fears of a longer than previously expected economic slowdown weighed on market sentiment but a strike at Peru's Cerro Verde mine exacerbated concerns over a tight supply situation. Benchmark copper on the London Metal Exchange was off 0.04 percent at $9,088 a tonne by 0955 GMT from a last bid $9,092 per tonne on Wednesday. It rose 1.8 percent in the previous session. "The very broad fear is that the economic slowdown may extend for longer than expected," said Credit Suisse analyst Stefan Graber. "The physical side of the market continues to be positive but increasing funding stress will trigger institutions to reduce exposure to risky assets such as base metals." A two-day strike by workers at Peru's third-biggest copper mine Cerro Verde heightened worries about supply constraints, although mine owner Freeport-McMoran said it does not anticipate "a material impact on production". Adding to supply-side worries, Freeport's Indonesia mine workers are set to strike from Sept. 15 to Oct. 15 unless the company meets their demands for a pay rise. "Yesterday's rebound showed that the base metals market is still supported by supply tightness and by resilient demand from all Asiatic countries," said Gianclaudio Torlizzi from metals consultancy T-Commodity. "Supporting this view is the fact that central banks in emerging countries have many more tools available in terms of monetary policy compared with developed countries and this, at least for the moment, will make them resistant to the slowdown affecting the U.S. and the EU." Putting pressure on copper, the euro eased against the dollar, as investors struck a cautious tone ahead of an European Central Bank rate-setting meeting at which policymakers are likely to flag a pause in its monetary tightening cycle. A stronger U.S. currency makes dollar-priced commodities such as base metals costlier for holders of other currencies. The economic growth worries gripping global markets were further highlighted by an OECD report that warned central banks to brace for weaker growth. The Organisation for Economic Cooperation and Development said on Thursday that developed countries face a sharp year-end slowdown led by a contraction in Germany. NICKEL SUPPLY Indonesia's industry ministry said that the country may impose a tax or quota on mineral ore exports ahead of a planned regulation to ban all exports of raw minerals by 2014. This will squeeze supplies of metals, including nickel, and support prices. "The Indonesian tax points to a tighter supply picture than previously expected, that is helping to stabilize nickel prices," Graber said. "Nickel demand has actually surprised on the upside and (stainless) steel production has been more resilient than expected. We are now at a price level where nickel pig iron producers are less competitive." Also pointing to improved demand for the metal, inventories of nickel in LME-approved warehouses fell to their lowest since February 2009 at $99,180 tonnes. This compares with a record high at more than 166,000 tonnes hit on Feb 2010. Nickel , used in stainless steel production, was at $21,818 from $21,775 at the close on Wednesday. Earlier, it hit its highest in more than a week at $21,950 per tonne. Tin was at $24,450 from $24,375 while zinc , used to galvanize steel, was at $2,223.75 from $2,240 at Wednes day's close. Lead was $2,409 from $2,415 and aluminium was $ 2,404, unchanged from the close. Metal Prices at 1015 GMT Comex copper in cents/lb, LME prices in $/T and SHFE prices in yuan/T Metal Last Change Pct Move End 2010 Ytd Pct move COMEX Cu 411.80 -0.30 -0.07 444.70 -7.40 LME Alum 2403.00 -1.00 -0.04 2470.00 -2.71 LME Cu 9092.00 159.00 +1.78 9600.00 -5.29 LME Lead 2415.00 0.00 +0.00 2550.00 -5.29 LME Nickel 21770.00 -5.00 -0.02 24750.00 -12.04 LME Tin 24375.00 0.00 +0.00 26900.00 -9.39 LME Zinc 2239.00 -1.00 -0.04 2454.00 -8.76 SHFE Alu 17435.00 10.00 +0.06 16840.00 3.53 SHFE Cu* 67720.00 -80.00 -0.12 71850.00 -5.75 SHFE Zin 17070.00 -75.00 -0.44 19475.00 -12.35 ** 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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