The $1.4-billion Tia Maria mine project has been the target of months of protests by locals who fear it will pollute their land and damage local agriculture.
Four people have been killed in the past two months as the protests have descended into clashes with police.
After protesters called a 48-hour strike from Wednesday for seven southern regions, the interior ministry announced it was deploying the army to the area until June 24 to bolster security.
The military "will only support the police and guarantee control and public order," the ministry said in a statement.
The 48-hour strike is for the regions of Apurimac, Ayacucho, Cajamarca, Cusco, Moquegua, Puno and Tacna.
It expands a strike in place since March 23 in Islay province, where the Tia Maria project is located.
Peru declared a state of emergency Friday in Islay, after a clash between protesters and police killed a 55-year-old demonstrator.
Southern Copper's local subsidiary, Southern Peru, which launched the project in 2009, called last week for a two-month "pause" to clear the air about the mine.
The firm and the government say concerns raised about the mine's original environmental impact studies have already been addressed, AFP reported.
Peru, the world's second copper producer and fifth gold producer, is banking on its mining sector to expand by four percent this year.