Nov. 11 (Bloomberg) -- Pretoria Portland Cement Ltd., Africa’s biggest manufacturer of the material, said it had been part of a cement cartel and was given immunity from prosecution for cooperating with antitrust authorities.

“It’s not a case of price-fixing,” Paul Stuiver, Johannesburg-based PPC’s chief executive officer, said in a telephone interview from Johannesburg today. PPC told the South African Competition Commission it shared detailed sales information through an industry group, he said, adding the company will stop that practice.

The commission, concerned that collusion in the building- materials industry raised infrastructure-project costs, is still investigating other cement producers including the local units of Lafarge SA and Cimpor Cimentos de Portugal SGPS SA and steel companies, including the local unit of ArcelorMittal.

Former employees introduced a practice of sharing information on sales. While current employees continued the practice, they won’t be punished as they weren’t aware the practice wasn’t allowed, Stuiver said.

“Our view is that the current pricing in the industry is at the correct level,” Stuiver said when asked whether the commission’s investigation will have an effect on prices.

Lafarge is not aware of any misconduct and will cooperate with the Competition Commission, Thierry Legrand, chief executive officer of the company’s South African unit, said in an e-mailed statement today. “We are extremely surprised by the allegations.”

Expansion Plans

South Africa, where PPC produces about a third of cement used, plans to spend 787 billion rand ($106 billion) over the next three years to expand power, rail and road infrastructure.

“For us the most important thing is to stop cartel behavior,” Nandi Mokoena, manager of strategy and stakeholders relations at the Pretoria-based Competition Commission, said from her mobile phone today. “It’s up to customers to claim damages,” she said, adding the law allows for that.

PPC shares gained 1.10 rand, or 3.4 percent, to 33.60 rand in Johannesburg trading, valuing the company at 19.6 billion rand ($2.67 billion).

The cement maker posted a 25-percent decline in net profit to 1 billion rand, while revenue rose 9 percent to 6.8 billion rand. Sales volumes may be similar next year to this year, Stuiver said, adding proposed electricity-price increases may boost operating costs by about 5 percent in the next year.

To contact the reporters on this story: Carli Lourens in Johannesburg at clourens@bloomberg.net.

Last Updated: November 11, 2009 12:03 EST