Harding's deficit view for the year is wider than the market consensus of around 400,000 tonnes and extends longer than many players predict of a more balanced market in 2013.

"I see a deficit ... It wouldn't be difficult to imagine something around the half a million tonne mark," Harding told Reuters on the sidelines of the CRU world copper conference. "I can image it being a one- or two-year phase and potentially longer."

Eoin Treacy's view The supply deficit in the copper market has been well reported over the last year and has more recently helped prices to sustain their move above $4. Major new supply is due to hit the market from 2012, with Ivanhoe's Oyu Tolgoi mine coming on stream as well as a number of other projects. However, until then, the market remains demand dominated. Any change to that situation will quickly become evident in the price charts.

Copper continues to hold above $4 and rallied impressively yesterday. A sustained move below the 200-day MA, which currently coincides with the 2006-2008 peak, would be required to question medium-term demand dominance. Copper, with tin, is a leader among the industrial metals. While these two metals are the only ones to have surmounted their respective pre-crisis peaks, the others are now also showing signs of increased bullish interest.

Tin remains in a steep relatively consistent medium-term uptrend. It found support at the upper side of the previous range in March and is now retesting the highs. A clear downward dynamic would be required to check potential for a successful upward break, while a sustained move below the MA would question the consistency of the medium-term uptrend.

The $2500 area offered support for aluminum in 2006 and 2007 but acted as a psychological barrier in 2009 and 2010. Prices have held a progression of higher reaction lows since June 2010 and continue to hold above $2500. A sustained move below that level would be required to question medium-term upside potential. Lead also appears to have completed a lengthy consolidation mostly below $2500. Zinc has lagged somewhat but also seems likely to sustain a break above $2500.

Nickel has found support in the region of the 200-day MA on a number of occasions since early 2009, mostly recently in March. A sustained move below $24,000 would now be required to question medium-term scope for additional upside.