Formal requests from the Australian Securities and Investment Commission to block Australian access to websites contained errors and may have skirted established law enforcement procedures at telecommunications companies.
Documents and emails released by ASIC under Freedom of Information on Friday revealed the financial services regulator sent requests to internet service providers Telstra, Optus, TPG and AAPT at least 10 times between October and April requesting them to block Australian access to websites.
On each occasion, ASIC requested that the provider block entire IP addresses rather than individual websites, meaning that potentially thousands of other websites would also be blocked from access for Australian users of any of the four companies.
Legitimate websites were inadvertently blocked on at least two occasions this year, covering more than 254,000 websites in total and prompting complaints from both civil liberties groups andtelecommunications companies.
The requests were made to the service providers using 15-year-old legal powers, known as Section 313 notices, which require internet service providers to cooperate with law enforcement where necessary.
But some emails containing the notices contained the wrong information and were pushed back by the internet service providers.
One request to Optus was sent to the company's network management centre, rather than its law enforcement team, and contained references to Pipe Networks, a subsidiary of TPG.
After an initial query by Optus's network staff, the company confirmed it had blocked the requested IP addresses for both business and residential customers.
An Optus spokesman said the company was reviewing its processes to ensure ASIC's requests went through the proper legal processes.
"Optus has a formal process to respond to requests from relevant government agencies," he said.
"We are currently reviewing how previous Section 313 requests were processed. Optus is in discussions with ASIC regarding the best approach to future requests."
Former communications minister Stephen Conroy last month confirmed he was looking into making the Section 313 process more transparent, while ASIC has committed to reporting annually on its use of the notices.
Sign up for Computerworld eNewsletters.