The economic development, tourism and environmental affairs MEC Nomusa Dube-Ncube said a “pipeline theft incident” resulted to the spillage of oil into the river in the Bellair area.
Transnet has reported about 80 incidents of fuel theft and attempted theft to the department.
Recorded cases of tampering with pipeline infrastructure with the intention to steal fuel were also reported.
Transnet currently operates and maintains a network of 3,800km of high-pressure petroleum and gas pipelines from Durban to Gauteng, which covers five provinces.
On Tuesday, one of these pipes was vandalised which led to the oil spillage that contaminated the river.
Dube-Ncube made it known that a team of environmentalists from her department and that of Transnet has been deployed to deal with the spillage and clean it up.
“It is for these reasons I have undertaken to visit the Umbilo River and all other affected areas in Bellair to assess the damage to the environment,” she said.
“I will ensure all spheres of government work in an integrated manner to strengthen measures undertaken by Transnet as part of cleaning and rehabilitating the source of the spillage and the harbour.”