Xstrata Copper's chief operating officer says overseas production has the potential to weaken copper markets later this year.
Analysts are optimistic overseas demand will help keep the price of copper stable.
However, Xstrata's Steve de Kruijff says an increase in production could cause prices to fall by the end of the year.
"So that means there will be more growth in the copper market which can then, if you've got more product coming in then that can reduce the copper price," he said.
"So we're still quietly optimistic that the first 6 months of this year will be positive, but going further into 2013 we're not so optimistic."