Lawmakers will vote in August whether to modify agreement, which may force the miner to make further concessions.

Three of four representative grab samples collected from the pit returned grades of 1.66%, 1.55% and 0.78% copper.

The government is seeking to free mining giant Codelco from a decades-old mandate to fund the country’s armed forces.

Ecuador’s ambition to become a mining superpower is being tested.

Negotiations, alternative employment programs and interventions by the police have failed to resolve the issue.

The dispute between the government and Vedanta started when Zambia appointed a liquidator to run Konkola Copper Mines and accused it of breaching its licence.

The project has the potential for an entire suite of strategic metals, the CEO says.