Tumbling global stock markets triggered renewed long liquidation at the London Metal Exchange, sending the three-month copper contract to a two-month low at 1,584 dollars a metric ton. The slide started in morning trade after a weak close for the Dow Jones. Industrial Average and follow-through falls for the Asian stock markets, with downward momentum picking up pace as key support levels at 1,610 dollars and 1,600 dollars/ton were broken.