Rio Tinto has announced the commencement of commercial production at Phase 1 of the A21 underground mine, part of Diavik Diamond Mine operations in the Northwest Territories of Canada.

The company has invested an additional $17m (£12.91m) into Phase 2 of the A21 underground project earlier this year, ensuring the mine's productivity through to its planned closure.

The construction phase of the A21 underground mine involved the excavation of more than 1,800m of tunnels to access the diamond-bearing ore.

As Rio Tinto prepares for the eventual closure of the Diavik mine, it continues to invest in reclamation activities.

These efforts include earthworks, site clean-up and equipment procurement, demonstrating the company's dedication to responsible mining practices and environmental stewardship.

Diavik Diamond Mine chief operating officer Matt Breen said: “The A21 underground operation is positive news for our employees, partners, suppliers and local communities in the Northwest Territories, as it will enable operations to continue through to closure.

“Rio Tinto’s decision to proceed with Phase 2 is a testament to the excellent performance of our Diavik team in successfully developing the underground mine beneath the previously mined A21 open pit.”

Last year, Rio Tinto announced plans to move forward with a $40m expansion at the Diavik mine, transitioning the existing A21 open pit into an underground operation, which will extend the mine's life until at least early 2026.

Phase one below A21 is expected to produce an additional 1.4 million carats while the second phase would produce a further 800,000 carats of rough diamonds.

The Diavik mine has produced more than 144 million carats of rough diamonds since mining began in 2003.