Allegations of corruption in the immigration department are serious and must be investigated, Foreign Minister Julie Bishop says.
But the department insists only a very small number of claims involve its staff and only a few cases are subject to ongoing investigation.
A joint ABC/Fairfax report on Monday alleged more than 130 cases of suspected internal corruption had been referred to the Australian Commission for Law Enforcement Integrity.
The report cited a former immigration official, who claimed internal investigations found "massive fraud" in the student, skilled migration and 457 visa programs.
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Ms Bishop said the claims should be thoroughly investigated.
"I'm sure that minister Peter Dutton will do just that," she told reporters in Perth on Tuesday.
"These are allegations that are serious."
However, the department said none of the allegations were new or unknown and some had been discredited.
"In some cases, the matters relate to investigations undertaken and concluded years ago," it said.
The department said all allegations relating to Commonwealth officials had been identified internally and where there was evidence, law enforcement partners were assisting with ongoing investigations.
"The Australian Border Force is also reviewing licensing arrangements for customs brokers to ensure appropriate scrutiny of those working in this key industry for border protection and will act to cancel or suspend licences where there is evidence of wrongdoing."
Labor leader Bill Shorten said if the reports were even half true, the government had undermined the visa system.
