Valdes and other high-ranking government officials met Tuesday with authorities from the Cajamarca region, where Conga is located, to discuss a proposal to use international consultants to review Conga's environmental-impact study.
The meeting resulted in an agreement to begin a review of Conga's environmental permit, which was approved in October 2010. The agreement said the cost of the review will be covered by Peru's government, Dow Jones Newswires reported.
The review is intended to resolve a dispute over the development of Conga, Peru's biggest mining project, which is 51.35% owned by Newmont Mining Corp.
Valdes told Radio Programas that the 40-day period to review Conga will begin on Wednesday. "We thought that 30 days was enough [time], but nevertheless we'll do it in 40 days," he said.
Environment Minister Manuel Pulgar-Vidal, who participated in Tuesday's meeting, said during a press conference that the consultants' review will provide the government with technical information about Conga's environmental impact.
"I'm sure that this review is going to provide us with the technical and scientific information to improve the process and make decisions," Pulgar-Vidal said.
While Peru officials are optimistic that the meeting on Tuesday was a step forward in resolving the dispute, many of the main opponents of Conga didn't participate and said they wouldn't recognize the agreement.
"It is a fake meeting," said Idelso Hernandez, head of a civil society group that has opposed Conga.
Opponents of the project said Tuesday that they sent a request to the Inter- American Commission on Human Rights, or IACHR, to have the project canceled.
Conga was suspended in late November following protests by groups that said the project will harm local water supplies, as the project would require draining four lakes. Newmont plans to replace those lakes with reservoirs, which it said would more than double the current water-storage capacity.
Compania de Minas Buenaventura SA has a 43.65% stake in Conga and International Finance Corp. owns the remainder.