By Julie Crust LONDON (Reuters) - Copper dropped as much as 8 percent on Thursday to a 33-month low on demand concerns amid mounting fears of a global economic slowdown. A U.S. Fed warning that the U.S. economy still faces significant threats and bleak U.S economic data led Wall Street to its worst day since the 1987 stock market crash. However, base metals pared earlier loses as European shares recovered somewhat from an early slide. "There is a very strong link between equities and commodities that will persist for the time being," Standard Chartered analyst Dan Smith said. Copper for delivery in three months on the London Metal Exchange fell as low as $4,545 a tonne, a drop of 7.6 percent, to the lowest price since January 2006. The metal, used in the contruction and power industries, traded at $4,820 a tonne in official rings after closing at $4,920 on Wednesday. Bullish news that workers had shut Chile's top mining port on Wednesday, delaying a copper shipment for at least one multinational company, was lost in the stream of negative data. Copper prices have fallen almost 50 percent since a record high of $8,940 a tonne in July. "Despite the collapse in copper prices, strike action by workers at mines and ports, particularly in South America looks likely to be an ongoing feature which will have an impact on supplies," Fairfax said in a research note. Aluminium was little changed at $2,178, after earlier falling as low as $2,115, from $2,170 a tonne. Prices for the metal -- used in construction, transport and packaging -- has fallen more than a third since a record high of $3,380 a tonne in July. Alexander Bulygin, chief exceutive of the world's largest aluminium producer United Company RUSAL said Thursday that 75 percent of aluminium producers in Europe, the United States and China were operating at below break-even with the metal trading at or below $2,500 per tonne. Aluminium stocks in LME-warehouses rose 9,225 tonnes to 1.47 million tonnes, the highest level since at least March 1995. LME zinc dipped to $1,242, after earlier falling to $1,206, from $1,255 a tonne on Wednesday. Prices near or below the marginal costs of production have forced some miners to cut back output and delay future projects. Strategic Resource Acquisition Corp said the credit crisis and falling zinc prices forced the company to reduce its Gordonsville zinc mine operations. Lead dropped as much as 7.9 percent to a low of $1,396 a tonne from $1,515 on demand worries for metal used in batteries. It was last quoted at $1,450/1,460. North American shipments of replacement automotive lead-acid batteries fell 8.6 percent in August from July, a U.S. industry group said late on Wednesday. While, J.D. Power and Associates, which tallies U.S. auto sales on a daily basis, sees October sales on track to hit the lowest level in 17 years. Nickel dropped $355 to $11,600 per tonne, while tin traded at $13,900 from $14,050. China has slashed export quotas for tin for next year by 30 percent from 2008, a government web site said.

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