South Africa's police directorate of complaints says it is investigating charges that more than 150 arrested striking miners have been beaten in police custody.

The news comes as President Jacob Zuma is being grilled by his African National Congress executive over the police shootings of 112 striking miners including 34 who died at Lonmin PLC platinum mine on Aug. 16. More than 250 arrested miners face charges from murder to public violence.

Directorate spokesman Moses Dlamini said miners allege they were beaten with batons and fists and kicked in efforts to get the names of miners involved in the killings of two police officers hacked to death in violence before the shootings.

Dlamini refused to comment on local reports that autopsies show most miners killed were shot in the back.