Peruvian President Ollanta Humala on Sunday declared a state of emergency in a mining region in the north of the country, which has been the site of a bitter conflict.

At the center of the conflict is the $4.8 billion so-called Conga project, an ambitious mining initiative operated by US mining giant Newmont, which has been drawing protests from local environmentalists.

"Using my constitutional powers, I introduce a state of emergency in the provinces of Cajamarca, Celendin, Hualgayoc and Contumaza," the president said in a statement.

He added the measure will take effect at midnight local time and continue for 60 days.

A worker strike has been underway in the area for 11 days.

The open-pit Conga project, located some 3,700 meters (12,140 feet) above sea level, involves moving the water from four lakes high in the mountains into reservoirs the company would build.

Protesters say the reservoirs do not adequately replace the lakes, which also provide groundwater for agriculture and to irrigate pasture fields for livestock.

The state of emergency allows authorities to place the troubled area under military control. It also suspends certain constitutional rights, such as freedom of assembly, freedom from unauthorized searches and seizures and the ability of people to travel freely across the affected area.

Cajamarca is Peru's leading dairy and livestock region, and the issue is of particular concern as a drought has forced water rationing for three months.

Deputy environment minister Jose De Echave resigned last month, calling official environmental impact studies on the project "weak, outdated and lacking in credibility."

Local officials, who support the strike, have repeatedly invited Humala to visit Cajamarca -- a department of 1.4 million -- but only Prime Minister Salomon Lerner and three other members of his cabinet made the trip.

Humala has backed the Conga project and blasted local leaders, calling them "intransigent."

Protests forced the closure last week of the airport in the city of Cajamarca as some 500 protesters besieged it and 100 passengers headed for Lima were left stranded.

Cajamarca, known as the city where the last Inca emperor filled a room with gold to pay ransom for his release from Spanish conquistadores, is located 870 kilometers (550 miles) northeast of Lima. The Spaniards kept the gold and killed the Inca emperor.