Mining giant Rio Tinto has agreed to sell its Eagle nickel and copper project in northern Michigan, US, to Toronto-based Lundin Mining for $325m, the first of several divestments planned by Rio in order to boost its balance sheet.

The deal is subject to regulatory approvals, and is expected to be completed in the third quarter of 2013.

Rio Tinto chief financial officer Chris Lynch said that the sale of Eagle demonstrates the company’s renewed focus and discipline in the way it allocates capital.

"We are making good progress on a number of other potential divestments as part of our goal to achieve substantial proceeds from divesting non-core assets," he said.

"Rio Tinto will continue to manage Eagle to the highest safety and environmental standards during the transition to the new owner," Lynch noted.

Construction on the Eagle project, which includes high-grade underground nickel-copper mine and mill., started in June 2010 and is nearly 55% complete.