A swimming event was postponed on Wednesday due to the unsuitable water quality of the Vaal River, the Emerald Casino Resort said.

"Based on information from Rand Water, the quality of the water in the Vaal River is not suitable for swimmers at this point," said chief executive officer Martin Rice..

One of the country's largest open water swim events, the Emerald Challenge, was scheduled for Sunday 30 November.

"Regrettably, we are postponing the Emerald Challenge until early next year, or such a time when we are satisfied with the quality of the Vaal River's water."

Rice said the comfort and safety of competitors and visitors to the property was of paramount importance.

Sapa