The ABC has revealed that thousands of Indian students, skilled workers and 457 visa holders have been admitted to Australia on dodgy travel and work documents.

Briefings prepared by the Immigration Department and obtained by the ABC's Fact Check Unit under Freedom of Information show out-of-control, large-scale fraud of the visa system.

The internal audits show fraud rates approaching 50 per cent, and an Immigration Department struggling to properly identify people who are entering the country.

"Identity fraud is a significant risk in the Indian caseload given how easily genuine documents with fraudulent details can be obtained," one document said.

Immigration Department spokesman Sandi Logan says the figures, from the 2008/09 financial year, are troubling.

"Around the periods of 2008, 2009, 2010 the fraud levels were quite considerable, a matter of real concern to the Department of Immigration and Citizenship," he said.

Documents reveal identity fraud Report of identity fraud

Report of identity fraud Integrity Alert Notice Read Immigration Department documents obtained by the ABC's Fact Check Unit under FOI laws.

He says things have since changed.

"We're quite confident that those people who were issued with a visa ... 99.9 per cent are who they say they are and are doing what they said they would do when they were granted that visa."

However in the papers, it is reported that the Department is nearly powerless to stop identity fraud, because of the low level of technology in Indian passports.

"Longer term, robust biometric processes embedded in Indian identity documents and in DIAC systems will be the only effective combatant," one paper said.

Man returns despite being deported, in debt

An Immigration Department eyes-only briefing from the New Delhi office, published in April 2011, bluntly describes its purpose is to "report on the ease with which identity fraud is possible in India".

The documents outline one alarming case where a man breached Australia's borders by entering the country under a false identity.

He had previously been detained and deported from Australia, and run up a debt with the Government.

He had also applied unsuccessfully for a protection visa, and had gone through all levels of appeal.

He was able to subvert the numerous visa checks by simply changing his birth date.

"During the interview, his wife admitted that he had lived in Australia, and he had withheld this information from the department," the documents said.

The man was eventually caught and re-deported, however the migration agent responsible for the fraudulent application was also living in Australia under a false identity.

The documents suggest that, in exchange for payment, the agent helped many others into Australia while avoiding detection.

Mr Logan says he is aware of the case.

"Human nature being what it is does mean there will always be people seeking to test, seeking to push to the limit, those regulations we have in place," he said.

Alarming fraud figures revealed after two-year wait

The ABC's Freedom of Information request took nearly two years - much longer than statutory required periods.

When the documents were delivered, they showed wide-scale passport, visa and ID fraud happening in alarming numbers.

For a General Skilled Migration visa class, from 23,767 visa lodgements there was a 46.9 per cent fraud rate for 2008/2009.

The fraud rate was as high as 51.6 per cent in the third quarter of the 2008/09 financial year.

For Indian student visas, the DIAC documents show a 37 per cent fraud rate from 41,636 lodgements across the same time period.

The fraud rate has raised questions as to whether the Immigration Department's existing security and processing systems can handle the growing and complex issue of identity fraud.

There does not appear to be much the Department can do, with one of the documents finding "opportunities to combat this type of fraud remain extremely difficult".

Calls for tighter regulation on overseas agents

Maurene Horder from the Migration Institute of Australia, the peak body for migration agents, says the situation has improved since 2009.

"There was clearly a major problem in India during the period of 2008, particularly with students coming to Australia. They were coming in great numbers," she said.

"People cheat about all kinds of things, around fraudulent marriages and do scams of all sorts and really that's a challenge for the compliance officers of our country whether they be the police or be they be immigration officials."

She wants migration agents overseas to be forced to register with the Department of Immigration, so they can be banned if they cheat the system.

"That was a porous, very bad system," she said.

"Now, some of those agents have been removed by the department and we think we should go even further with that and actually only allow people who are trained and registered migration agents to be dealing in that space."