The Department of Human Services is refusing Freedom of Information requests on its new automatic debt recovery program.
In at least eight cases, the department has attempted to refuse or delay the release of documents because it claims it is "not clear" which program the request refers to, could not find relevant documents, or found too many documents.
Centrelink has issued nearly 170,000 notices of potential overpayment of welfare benefits since July.
In about 20 per cent of cases, the individual has been found to not owe any money.
The program has been the subject of fierce political debate and intense media coverage and it is now the subject of a Senate inquiry.
The Department of Human Services, however, is apparently unaware of it.
In another request lodged through the website righttoknow.org.au, the department claimed it could not find any documents about the risks of the automated program.
"All reasonable steps have been taken to locate the documents you have requested and I am satisfied that they do not exist," the department's FOI team wrote.
But in a third case, the department said it was refusing the request because there are too many documents.
"I am unable to reasonably identify what documents you want due to the volume of documents," it said.