South Africa's Palabora Mining said its magnetite exports would be hit after a derailed train damaged a bridge on the railway line linking its mine with the ports of Richards Bay and Maputo.

Palabora, partially owned by Rio Tinto , produces magnetite -- a type of iron ore -- as a by-product of its copper production.

"The railway incident will principally impact the shipment of Palabora's magnetite to the ports, which will consequently have an impact on sales revenue," it said in a statement.

The company produced 1.37 million tons of magnetite in the six months to the end of June this year.

Logistics group Transnet which operates the line, said some 15 out of 80 wagons carrying rock phosphate derailed on the line.

The Brakspruit bridge, in South Africa's Limpopo province, will be out of service for at least five weeks, a Transnet spokesman said. He could not yet confirm if companies other than Palabora would be affected by the damage. (Reuters)