BHP Billiton has invited initial bids for the undeveloped coal prospecting rights of its wholly-owned unit in South Africa, The Australian reported. BHP Billiton Energy Coal South Africa has invited coal exploration, mining and development companies to apply to take part in the tender process for the sale of its entire interest and prospecting rights at Hartogshof, T-Project, Davel, Pegasus, Theunissen, Waterberg, Newcastle, Ermelo and Remhoogte. BHP Billiton’s South African unit supplies thermal coal to the local and export markets.