Some 5,600 mineworkers at the world's top platinum producer Anglo American Platinum downed tools overnight at the firm's South African operations, demanding the reinstatement of suspended union leaders, the company said Monday.

Workers at the volatile Rustenburg mining belt in the North West province want the company to reverse the suspension of 19 shop stewards belonging to the militant Association of Mineworkers and Construction Union (AMCU), who took part in an illegal sit-in last week.

"This impacted the night shift last night at Thembelani (mine) and the morning shift today at Thembelani and Khuseleka 1," the company said in a statement.

The strikers also demand an office of the rival National Union of Mineworkers (NUM) at Amplats be closed.

The AMCU has overtaken the once dominant NUM as the majority union in the mine. Rivalry between the two has resulted in deadly clashes at various mines across the country, which halted production.

Early this year, Anglo announced plans to cut some 14,000 jobs in a bid to cut costs accrued during lengthy wildcat strikes. The figure was later revised to 6,000, amid protests from unions and the government.

This month, mining companies and unions signed a government-backed peace pact to end violence which has plagued the sector since the August 16, 2012 shooting of 34 striking miners in Marikana during a protest.

Anglo American urged the workers to comply with the peace accord "to promote the peaceful co-existence of all the recognised unions at our operations."

Mid-year is wage bargaining season in South Africa, which often results in workers taking part in rolling mass protests over wage disputes.