TAXATION Commissioner Michael D'Ascenzo has disputed the contents of an internal Tax Office report that suggested criminals had stolen more than $5 billion in tax revenue by setting up false companies and receiving illegal refunds.

Mr D'Ascenzo said yesterday that the report on criminals submitting false Business Activity Statements was written by an officer who had since left the ATO. It is believed that the officer, a former senior investigator, wrote the report and made recommendations on his own initiative.

"The information and figures (in the report) do not reflect the facts," Mr D'Ascenzo said. "We have wide-ranging controls to detect and stop fraudulent refunds and continually monitor and enhance them. If anything, various external reviews of our processes have raised concerns about the stringency of our checks and balances."

The Age published details of the internal report on Monday. The report warned that up to $1.4 billion a year was being stolen by criminals setting up bogus companies and receiving huge amounts of illegal tax refunds. This type of tax fraud was spreading through the Australian prison system, and Tax Office sources have told The Age that criminal gangs in Asia are targeting Australia's tax revenues.

Mr D'Ascenzo rejected the report's findings that criminals were able to register firms and gain business numbers without having to provide tax file numbers or legitimate addresses.