Australian immigration officials are dealing with about 24,000 freedom of information requests each year, roughly 60 per cent of all such applications lodged with the Commonwealth.
The number of requests to the department has soared by almost 10,000 since 2013-14 and is on track to surpass 24,000 this financial year.
Immigration staffer Ben Wright agreed there was a backlog, saying the department had experienced a significant increase in FOI requests and the staff were processing a large number.
"If I could have a lot more staff (to handle the requests) I would but unfortunately I live in the real world and we've got to make do with what we've got," he told a Senate estimates hearing in Canberra on Monday.
Mr Wright took on notice questions around how many requests were processed on time and how many extensions were sought.
He was also quizzed about an email an immigration official accidentally sent to The Guardian website last year alleging a freeze on the release of documents for asylum seekers held in offshore detention.
The similarity in the names of the officer's boss and a reporter at The Guardian was behind the misdirected email, and the man's use of the term "freeze" was wrong.
"He is one of our better performers and he was devastated when he made this error," Mr Wright said.
© AAP 2018