The blockade, in place since Nov. 20, threatens to halt output at the Chinese-owned mine in southern Peru, which produces some 2% of the world's supply of copper.

The two sides are $8 a tonne apart on where they would like the treatment charge benchmark to be.

The battle over mining in Ayacucho is a flashpoint for the new government as well as for global metal markets that rely on Peru’s rich deposits.

The mining corridor, as the road is known, has been blocked for over 400 days since Las Bambas began operations in 2016.

Prices are up 20% this year while a wider index of industrial metals is up nearly 30%.

In the past two weeks, two other Chinese companies have both announced plans to produce 40,000 tonnes per year of matte in Indonesia.