BUENOS AIRES (Reuters) - The Argentine government will step up security in the Vaca Muerta oil fields by placing the shale formation under the jurisdiction of the military police, the Ministry of Security said on Monday.

Vaca Muerta is viewed as a key source of foreign exchange for Argentina´s struggling economy by both President Mauricio Macri’s government and opposition Peronist candidate Alberto Fernandez. Macri and Fernandez will face each other in the October election.

Having attracted the attention of foreign oil companies in recent years, the shale play has also become the target of protests by unions, environmentalists and indigenous groups.

“It is imperative to safeguard the physical integrity of the hydrocarbon essential to provide physical protection to the facilities in the Neuquén Basin,” a statement from the Security Ministry said.

Vaca Muerta, which covers an area about the size of Belgium in the southern region of Patagonia, is thought to contain one of the world’s largest reserves of unconventional oil and gas, and remains largely untapped.