Virga said 53% of the 2012 increase in global growth of refined copper supplies occurred in the fourth quarter.

FORBES: FOCUS: Copper Market 'Guarded;' Near-Term Bounce Occurring But Longer-Term Retreat Expected

Catherine Virga, director of CPM Group, said the consultancy had estimated an end-of-2010 Chinese inventory of at least 1.63 million tons.

FORBES: FT Story On Chinese Copper Inventories Captures Attention, But Impact Likely To Be Muted

Virga said if the Grasberg strike is extended again, an additional 15 to 24 million pounds of copper production could be lost.

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Virga doubts metals will pull back to their August lows on any correction, looking for them to hold in a higher trading range.

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Virga said she is cautious about how much stimulus to expect from China, as some cities may have trouble coming up with further funding.

FORBES: Average Base Metals Prices Expected To Fare Better In Coming Quarters; Gains Seen As 'Moderate'

It helps explain why China has been in a de-stocking phase, but the country is likely to remain price-sensitive in its purchases, Virga said.

FORBES: FT Story On Chinese Copper Inventories Captures Attention, But Impact Likely To Be Muted