A major stakeholder in the Pebble Mine partnership has announced it will be withdrawing from the project and giving its share to two Alaska charities.

Multinational metals company Rio Tinto announced Monday it will gift its 19.1 percent stake in Northern Dynasty Minerals Ltd.—the owners of the Pebble Partnership—to the Alaska Community Foundation and the Bristol Bay Native Corporation Education Foundation.

The announcement states the 19.1 percent share “will be divided equally” between the two charitable foundations “to fund educational and vocational training … (as well as) educational and cultural programmes in the region.”

Rio Tinto Copper chief executive Jean-Sebastien Jacques said the company “continue(s) to see Alaska as an attractive location for potential future investment.”

Dividing the shares between the charities “ensur(es) that Alaskans will have a say in Pebble's future development and that any economic benefit supports Alaska's ability to attract investment that creates jobs," Jacques said.

In December 2013 the company announced a “strategic review” of its involvement with the project, with divestment a possible outcome.

The move is the latest in a series of setbacks for the Pebble Partnership, which has been seeking to build a gold, copper and molybdenum mine in the Bristol Bay region for nearly a decade.

In March the Environmental Protection Agency announced it would implement a rare and aggressive form of environmental review of the project under the Clean Water Act. That review will delay the Pebble project by at least one year and ultimately could restrict or even prohibit development of the mine.

U.S. Senator Lisa Murkowski wrote in a Monday statement that, while she applauds the company's divestment through Alaska charities, she's concerned that federal regulation may have influenced the decision.

"If we want to attract investment to our state and our economy, we need a regulatory system at the federal level that is predictable enough to allow responsible development to go forward – at least to the permitting stage, and without the threat of a preemptive veto from the EPA hanging over it," Murkowski wrote.

Beyond the partnership's regulatory setbacks, the group also lost one of its key investors in September 2013 after United Kingdom-based mining giant Anglo-American PLC announced it would be pulling out of the project.