A section of the Sappi Saiccor plant in Umkomaas, south of Durban, has been shut down following a gas leak earlier in the week, the plant's chief executive Alan Tubb said on Friday.

"We hope to find the root cause of the problem soon and until then it will remain closed," he said.

A team of environmental experts was expected to investigate why 48 people were exposed to toxic sulphur dioxide gas.

Khulekani Ntshangase, spokesperson for the agriculture and environmental affairs department said on Friday they would have to determine whether the leak was an accident or the result of human error.

"We have also told the plant that they need to give us a report on the incident within 14 days. Then once we determine whether the leak was an accident or caused by human error, we will decide whether to penalise them or not," he said.

Sappi, a global producer of coated fine paper and chemical cellulose, confirmed that 34 mill employees and 14 residents were affected by a sulphur dioxide leak in the plant's newly commissioned pipeline on Tuesday night.

The employees were treated at the mill's hospital and discharged.

The affected residents were assessed at GJ Crookes hospital in Scottburgh. They were discharged the same night.

According to online encyclopaedia Wikipedia, inhaling sulphur dioxide gas results in laboured breathing, coughing, a sore throat. It may cause permanent lung damage. It also causes redness and pain to the eyes.

Sappi general manager Gary Bowles said technicians at the mill were able to isolate the malfunctioning pipeline. He gave assurances that precautions would be taken to prevent further emissions.

"The mill has procedures in place to deal with eventualities of this nature on a priority basis, and we were able to contain the leak promptly," he said, adding that the incident was regretted.

Sapa