"I can't actually give you a number of what the deficit will be ... but I can say it will be meaningful," Harding said. "And it will be large enough that the strategic reserves that people are holding will be largely consumed."

Harding said that although Rio Tinto's copper output surged almost 15 percent in 2009 to just over 800,000 tonnes, it would likely struggle to maintain production due to declining ore grades until 2013.

He said the improved company output was due primarily to Rio Tinto's Kennecott Utah mine where production rose nearly 30 percent in 2009 with improvements to its concentrator.

Chile's Escondida, the world's largest copper mine where Rio Tinto has a 30 percent stake, also reported a 30 percent increase in copper concentrate in the fourth quarter, after repairs to its SAG mill.

The massive Mongolian Oyu Tolgoi project is due to come on-stream in 2013, sharply reversing any declines in Rio Tinto copper output in the coming years. The project is forecast to put out 450,000 tonnes a year on average over the next three decades.

Rio Tinto has a 22 percent stake in the project, and warrants that will allow it to raise its share to 46.6 percent. It is partners in Oyu Tolgoi with Ivanhoe Mines Inc and the Mongolian government's sovereign fund.

Further into the future, Harding said the company's underground Resolution copper project in Arizona, the largest in North America, is expected to come on-stream around 2019 and to produce copper, gold and molybdenum for decades to come.

Eoin Treacy's view The copper price encountered resistance in the region of $3.50 in January and pulled back sharply to the 200-day moving average where it found support. It broke upwards last week and sustained the move this week. While one might expect prices to pause in the region of the previous highs near $4, a downward dynamic would be needed to check momentum and a sustained move back below the MA, currently near $3, would be required to question medium-term upside potential.