A US-based labour rights group has filed a lawsuit against three big food companies after an industry pledge to establish a certification system to help eradicate child labour on West African cocoa farms passed its deadline.

The International Labour Rights Fund (ILRF) filed the suit against Nestlé, Archer Daniels Midland and privately held Cargill last month, on behalf of three Malian children who were allegedly trafficked to work on plantations in Ivory Coast, beaten and forced into hard labour. The preliminary hearing is expected to begin next Monday.