By Tiisetso Motsoeneng JOHANNESBURG (Reuters) - South Africa's competition watchdog raided the local units of Unilever Plc and Sime Darby Bhd on Thursday as part of a probe into suspected price fixing of edible oils and margarine. The Competition Commission said in a statement it searched and seized documents and electronic data from the offices of Unilever South Africa and Sime Darby Hudson and Knight. Sime Darby Hudson and Knight is a South African producer of oils and fats and a unit of Malaysia's Sime Darby Bhd, the world's top palm oil planter. "The Commission believes that the information that will be obtained from today's operation will enable the Commission to determine whether or not Unilever SA and Sime Darby have indeed engaged in collusive conduct," Acting Commissioner Tembinkosi Bonakele said. Unilever and Sime Darby said they were cooperating fully with the Competition Commission. "We are in the midst of gathering further information on current investigations into alleged contravention of the South Africa’s Competition Act," Sime Darby said in a statement. Previous investigations by the commission include a probe into suspected collusion in the petrol market, involving Royal Dutch Shell, Chevron and Sasol. The Competition Tribunal, which makes the final call on all antitrust cases, recently handed a 1.5 billion rand ($141.41 million) fine to 15 construction firms to settle a multi-year investigation into bid-rigging.($1 = 10.6078 South African Rand)