Australian Federal Police (AFP) accessed more than 40,000 phone and computer records last year without a warrant.
Revelations in a Senate estimates hearing in May also show efforts by the AFP to obtain Facebook and Google data, according to Fairfax media.
It comes as controversy rages over the US National Security Agency's (NSA) controversial PRISM program, details of which were leaked by whistleblower Edward Snowden.
Under PRISM, which has been running for six years, the NSA can issue directives to internet firms demanding access to emails, online chats, pictures, files, videos and more uploaded by foreign users.
Less than two weeks ago, AFP deputy commissioner Michael Phelan reportedly told a Senate estimates hearing that last financial year, federal police made 43,362 internal requests for "metadata" on Australians' phone and internet records.
No warrant is required for this type of information, which includes the phone number called, the time of the call and its duration.
Independent senator Nick Xenophon says the revelation is worrying.
"These problems on metadata could turn into a mega-problem for our democracy," he told Fairfax media.