By Peroshni Govender JOHANNESBURG (Reuters) - South Africa's government on Friday appointed veteran public service executive Brian Molefe as acting CEO of its struggling power utility Eskom to help keep the lights on in Africa's most advanced economy. Power constraints are seen as a key constraint to already sluggish South African economic growth and are an irritant for households and businesses alike. Molefe, who steps down as the chief executive of the state transport firm Transnet [TRAN.UL], replaces Tshediso Matona, who was suspended pending an inquiry into Eskom's mounting woes. Public enterprises minister Lynne Brown told a news briefing that she wanted someone who could "do the job from the get go" at the utility which on Friday said it had to implement rolling blackouts for the sixth straight day. "I need the capability of somebody who had held a leadership role in a state-owned company that's almost as large as Eskom and who has turned that company around," she said. Eskom said it would expand its power cuts to 2,000 MW on Friday to prevent the grid from collapsing. Molefe said his priorities would be to tackle generation problems, increase efficiencies, and reduce the utility's dependence on coal, which accounts for close to 90 percent of the power Eskom produces. "To deal with current problems of generation, increase efficiency to provide electricity and reduce dependency on coal," Molefe said, referring to his main priorities. Eskom is battling to keep the lights on in Africa's most advanced economy and faces a serious liquidity crunch. It has to resort frequently to controlled power cuts to prevent the grid from being overwhelmed. Molefe's replacement at Transet, which runs South Africa's rail and port network, will be decided on Monday, and there were three candidates being considered, Brown said. A senior Transnet executive said it was likely that Siyabonga Gama, the respected head of Transnet's rail freight operations, would replace Molefe as head of the overall group.