Norway's $900-billion wealth fund can no longer invest in Duke Energy, the biggest U.S. power firm by generation capacity, due to alleged breaches of environmental law at its coal-fired plants, Norway's central bank said on Wednesday.
The fund, which owns 1.3 percent of the world's listed company equity with stakes in some 9,050 firms, is barred from investing in companies that make nuclear weapons, anti-personnel landmines or tobacco, among other ethical criteria.
Duke Energy and its subsidiaries Duke Energy Carolinas, Duke Energy Progress and Energy Progress Inc were excluded "based on an assessment of the risk of severe environmental damage", the central bank's board said in a statement.
At the end of 2015, the Norwegian fund, the world's largest, held 0.62 percent of Duke Energy, a stake worth $304 million, but it has since sold the shares in Duke and its subsidiaries.
The board's decision was based on a recommendation by the ethics watchdog for the fund, the Council on Ethics.
"For many years, these companies have, among other things, repeatedly discharged environmentally harmful substances from a large number of ash basins at coal-fired power plants in North Carolina," the watchdog said in a separate statement.
"Several court rulings have ordered the companies to remove or seal these ash basins. In its assessment, the Council places emphasis on the fact that the planned measures will not be fully implemented for another 10-15 years," the ethics council said.
The council also said it perceived, "the long-lasting and extensive breaches of the environmental legislation to be a considerable risk factor".
Duke Energy said the fund had signaled its intention for some time but it was nevertheless disappointed.
"It is unfortunate that (the fund) did not consider Duke Energy's proactive actions to enhance our environmental stewardship and close ash basins across our jurisdictions," the firm said in an emailed statement to Reuters, adding that it had made "significant progress".
"Since 2011, we have retired more than 40 coal units across our generation fleet and this process will continue," it added.
Some 113 companies and their subsidiaries have so far been excluded from the wealth fund on ethical grounds. Two are under observation, including Brazil's state oil company Petrobras.