Some Krugerrands have been found to be underweight with too little gold used in their manufacture, the Sunday Times reported in its first edition on Saturday evening.
The newspaper said the SA Mint Company, a subsidiary of the Reserve Bank, had admitted that it made underweight proof or collector Krugerrands.
In a statement on Friday the Reserve Bank confirmed that the coins in question were produced in April and May 2011.
A rand sells for about R14000 and is the world's most popular gold coin and one of South Africa's most famed collector's items.
According to the Sunday Times, coin dealers were called to the SA Mint Company last year and told about the problematic coins. Apparently they had to sign a confidentiality agreement that forbade them from talking about what they knew.
The Reserve Bank had told dealers that suspect coins would be exchanged by the SA Mint Company. - Sapa