In an interview published on Saturday by the newspaper La Tercera, the firm's executive president Iván Arriagada cited election uncertainty and took aim at "violence" as a source of pressure. The country has grappled with regular protests in recent years and is now redrafting its Constitution.

"What we have seen in the last year and a half is an increase in the levels of uncertainty due to political discussion and a significant degree of polarization. These are factors that we undoubtedly look at with concern," he said.

Chile is the world's largest copper producer.

Polls show that the favorites in the Sunday vote are ultra-conservative lawyer José Antonio Kast and left-wing congressman and former student leader Gabriel Boric, who are widely expected will face off in a second-round ballot in December.

The elections take place two years after an outbreak of demonstrations against inequality that brought many people to the streets. Many of the protests ended in clashes with police.

Mining companies operating in Chile have raised concerns about rising uncertainty and underlined the importance of maintaining the rules of the game that have allowed the rapid development of the sector in the country.

Arriagada did say that the copper market has good long-term fundamentals, with sustained demand, which should help keep prices at the current high levels - above $4 per pound - for the next 12 to 18 months, albeit with greater volatility.