LIMA, Peru (AP) — Union workers at more than 50 mines in Peru have gone on strike to protest parts of a labor reform that they say will harm workers' rights.

Ricardo Juarez is leader of a national federation of miners. He says the strike is "indefinite" and 90 percent of unions have joined.

Juarez argued that laws approved by President Pedro Pablo Kuczynski would make it easier for mass layoffs and weaken inspection bodies.

The protest targets mining activity in the world's second-biggest copper-producing nation.

But Energy and Mines Minister Gonzalo Tamayo said Wednesday in an interview with Radioprogramas that the strike's effect "is relatively limited."

He said mine companies have back backup plans and equipment.