The controversy over the £3bn (US$4.8bn) Minas Conga gold mine planned for Cajamarca continued this month.

The mine’s operator, US-based Newmont Mining, received a boost on 18th April when Peru’s Constitutional Tribunal overruled an effort by Cajamarca’s regional government to block the project.

Local authorities had attempted to stop the mine by passing a regional government order, declaring the project unviable and illegal. However, this month the higher court ruled that in doing so Cajamarca’s government had acted outside of its mandate.

In response to the court’s decision, representatives from a number of organisations opposed to the mine announced plans for a general strike in the area. Gregorio Santos, head of the regional government and staunch Conga opponent, added that he would continue to lobby officials to block the project’s development.

In a separate development on the same day, an international panel convened by the government to review Conga’s environmental impact assessment (EIA), announced its conclusions. The panel declared that Newmont would need to make “substantive improvements” to its plans before continuing with the project.

Their 260-page report recommended that the firm be allowed to excavate and replace only two lakes in the project area (current plans are for four lakes to be removed). The panel also proposed that tailings pools should be relocated, that waste sites be secured from water treatment plants and that soil conservation methods be improved.

At a press conference in Lima, Environment Minister Manuel Pulgar said the government would analyse the panel’s conclusions in coming months to establish new parameters for the project.

Santos meanwhile hailed the report as a clear victory. Others, such as hydrological engineer and former president of the Cajamarca Environmental Defence Front Reinhard Seifert, were more cautious, warning that longer-term studies were required to fully assess the project’s environmental implications.

Shortly after the panel announced its findings, Newmont CEO Richard O’Brien said the recommended changes could significantly affect the mine’s profitability. The firm is now considering whether to divert funds earmarked for Conga into projects outside of Peru.