Fund activity in the metals markets is making copper prices more volatile, Antofagasta said on Tuesday.

Announcing an 8.4 per cent rise in first-half pre-tax profits to $1.44bn (£720m), the Chilean-based, London-listed miner said prices would remain strong into 2008, but added that “the increased role of investment funds in commodity markets has made base metal prices more sensitive to changes in market sentiment, and accordingly short-term copper prices are expected to remain volatile”.