US President Donald Trump's outgoing administration is set to approve a controversial land swap later this month that would give Rio Tinto and partners more than 9.7 km² to build an Arizona copper mine, even though the project would destroy religious and cultural sites to Native Americans.

Tribal leaders and other critics allege that the US government is fast-tracking the environmental review process before Trump is replaced by President-elect Joe Biden next month, charges the government and Rio Tinto deny.

The land swap, outlined in US government documents, reflects the tension between the increasing global attention on the rights of indigenous peoples and the need to boost metals production to power electric vehicles and reduce global carbon emissions. Copper is used to make solar panels, wind turbines and EV batteries.

The San Carlos Apache Tribe says the mine, if built, would destroy land considered the home of religious deities and sites used for tribal ceremonies, including one to celebrate teenage girls who have come of age.

"This is about religious freedom," said Terry Rambler, chairman of the San Carlos Apache Tribe. "For me and our people, it's a fight not only for today, but for our children and grandchildren."

Rio and partner BHP Group have sought for years to access the underground copper deposit in the Tonto National Forest, which abuts the San Carlos reservation.

A last-minute addition to a 2014 Pentagon funding bill signed by former President Barack Obama allowed Rio to exchange land it owns near the forest for land above the copper reserve, with the caveat that the swap could not occur until an environmental study was published.

The US Forest Service has changed its publication estimate several times. Last April, the agency said it would come in 2021. Three months later, that was changed to December 2020 because the agency said it has been completing its review faster than expected.

The Forest Service referred requests for comment to a December 1 statement where it said the plan for December publication "does not reflect an acceleration."

The San Carlos Apache tribe have worked with mining companies in the past, most recently selling water to a mine owned by Freeport-McMoRan, though the tribe said that was a decision they made themselves, not one decided by the US government, as with the land swap.

Rio said that its Resolution Copper subsidiary, which is developing the mine, has not tried to expedite the permit process.

"The project is not being 'fast-tracked'," the company said, adding that if the land swap occurs, the Apache will be able to visit the land for the next few decades.

Rio faced criticism earlier this year for destroying indigenous sites in Australia. Native Americans say the mining giant is poised to make the same mistake in Arizona.

Rio said it has consulted with the San Carlos and other Arizona tribes about preserving other culturally significant locations, including Apache Leap, a rock cliff where in the late 19th Century Apaches jumped to their deaths to avoid capture by US troops.

Biden was overwhelmingly supported in last month's US Presidential election by Native Americans across Arizona, exit polling data show. Tribal leaders are already lobbying the incoming president to block construction permits for the mine.

Rambler, the tribal chairman, said Biden's transition team is considering his request to meet with the president-elect.