The Department of Social and Family Affairs has denied the computer system that issues Personal Public Service (PPS) numbers is open to fraud because it cannot recognise "foreign names".
Some media reports had suggested the system did not recognise such names and was therefore unable to detect if a foreign national applying for a PPS number already had one.
However, a spokeswoman for the department insisted this and other claims of shortcomings in the system were "incorrect" and had been "corrected publicly" after concerns about the system were raised in the Comptroller and Auditor General's report last year.
"The department is in fact able to check if a non-national name is on the database and the system does screen foreign names," the spokeswoman said.
A number of "fraud and error surveys" had been instigated by the department, she said, "and results so far indicate that identity fraud is not as significant an issue as implied by the C&AG report".
A number of measures had nonetheless been taken to improve the security of the system, including better training, more rigorous processing of applications and the installation of ultra-violet scanning equipment, the spokeswoman said.