Copper futures fell over one percent in American trade, heading for the fourth daily decline in six sessions away from the highest since September 16, 2014, as the dollar index rebounded from the lowest since January 2, 2015, following earlier data from the US. 

As of 02:21 GMT, copper futures due on December 15 tumbled 1.48% to $299.10 a pound from the opening of $303.60, while the dollar index rose 0.08% to 91.95 from the opening of 91.88. 

Earlier US data showed producer prices rose less than expected in August, while core prices widened also below forecasts, as yearly readings for both accelerates below expectations as well. 

Copper is moving away from three-year highs and plumbing the lowest since August 23 on profit-taking, especially as the dollar flexed its muscles as concerns dissipate over the North Korea nuclear crisis and Hurricane Irma. 

Otherwise, the latest report from commodity analysts at Commerzbank said that many experts believe that the copper market is facing a speculative surge on a wide level that's not properly based. 

The report pointed to Chilean state-owned copper mining company Codelco as an example of recent speculation, while noting that the company itself said recently that copper prices are considerably above their reasonable limits, and that gains in recent months were not sustainable, after copper prices rose 24% year-to-date, compared to 15% for gold and 11% for silver. 

Some analysts predicted surpluses in the copper market in the long term, pointing to already existing surpluses that could carry on for two years, especially as Chinese demand slows down. 

Copper prices could tumble in the coming period as Chinese housing sales drop while credit growth in China slows down alongside mining inventories in the world's largest metals consumer.