The fund is a major shareholder in some of the world's largest mining companies, including BHP Billiton, Anglo American and Glencore Xstrata.

"Companies that are having an activity that create huge externalities may over time get problems either through greater regulation, through lawsuits or through other ways of pricing the effects that they have on the external environment," Yngve Slyngstad said on the sidelines of a news conference.

Asked which sector the fund would be looking at this year, Slyngstad said: "The obvious one that has the largest environmental impact is mining ... There is environmental damage by definition."

"It does not mean that we are selling out of the sector. We are concentrating our investments on the companies that we think are continuing this activity in a more sustainable way," he said after presenting the fund's 2013 results.

The fund's chief also said companies' boards, rather than investors, should decide on the pay packages of top executives.

"We think (it) is wrong. Boards are better positioned to make those decisions," he said, adding that the fund had voted against pay packages that were not sufficiently understandable.

(Reporting by Gwladys Fouche and Camilla Knudsen)