Its business confidence index (BCI) fell to 90.4 in March from 93 in February, its lowest level since April 2000, when the BCI measured 89.1.
Sacci said the business climate was at a "disturbingly low" level.
"The BCI continues its downward trend while the South African economy is officially still in an upward phase of the business cycle," Sacci said. "The short- and medium-term changes in the BCI in March reflect tentativeness and continued volatility in the business climate.
"The financial environment was more restrictive than a year ago and may weigh on an already stressed real economy. The continued weakening of the rand is of special concern while inflationary expectations could be on the rise."
A separate survey from the Bureau of Economic Research and Rand Merchant Bank showed business confidence improved in the first quarter of this year, but not strongly enough to suggest the start of an upward trend.
Its business confidence index rose to a reading of 52 from a reading of 46 in the fourth quarter of last year.
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