Fairfax Media has confirmed Australian law-enforcement agencies are using a technique known as a "tower dump", which gives police data about the identity, activity and location of any phone that connects to targeted cell towers over a set span of time, generally an hour or two.

A typical dump covers multiple towers, and mobile providers, and can net information about thousands of mobile phones.

The dumps are usually used in circumstances when police have few leads and can be a useful, powerful tool in tracking down criminals. But privacy advocates say that while they may be helpful to police, they also target thousands of innocent people and don’t have any judicial oversight.

In addition to no warrant being required to request a tower dump containing the mobile phone data of thousands of people to track down one or more criminals involved in a crime, privacy advocates also question what is being done to the data collected once an investigation is complete.

USA Today initially reported how US law-enforcement agencies were using the tower dump tactic earlier this year.

NSW Police, Victoria Police and the Australian Federal Police all declined to comment.

But Fairfax Media has been able to confirm that "tower dumps" were an investigation tool often used by NSW Police.

A NSW Police spokesman said it would “not comment” on its “operational capabilities”.

Victoria Police wouldn't discuss tower dumps either, saying it did not comment on "police methodology”.

And the Australian Federal Police also said it would not comment on its "technical capabilities”.

Some phone companies receiving the requests, however, admitted that tower dumps occurred.

“On occasion mobile network operators receive requests from Australian law-enforcement agencies to provide communications information from a specific tower,” a Vodafone spokeswoman told Fairfax. “These requests usually cover short periods and the information provided is only metadata.”

Metadata is information about the time, duration and destination of calls but not their content. Metadata can also include location data about a mobile phone, even when it’s not on a call.

Telstra wouldn’t say whether it received tower dump requests but believed they were lawful.

“A request for non-content information on the use of a particular tower during a specified period of time may be lawful under certain circumstances,” a Telstra spokeswoman said.

Meanwhile, Optus would not comment on the tower dump practice at all, saying instead that it assisted “law-enforcement and national security agencies as required in the legislation...”

Greens Party spokesman for communications, Scott Ludlam, said this was the first time the practice of tower dumps had been confirmed to occur in Australia.

“It’s another example where [agencies] are collecting the entire haystack in order to find the needle,” Senator Ludlam said in an interview with Fairfax.

“What we've seen with other techniques like this is there is no requirement to destroy the material that is collected incidentally after an investigation is complete,” Senator Ludlam said.

He added that he would like to see more transparency around what type of crime needed to be committed in order for tower dumps to occur.

“What we need is transparency as to what's being done and who is doing it,” he said. “Ultimately I think we need a lawful warranting process to start to apply to [requests for data] like this.”

Although the Attorney-General’s Department releases a once-a-year report detailing how many requests are made to telecommunications companies for metadata in Australia, it’s unclear whether a tower dump is counted as one metadata request or otherwise.

Considering thousands of users are affected by tower dumps, Ludlam argues that they should count for the number of those who are affected.

Around 330,000 requests for metadata were made by law-enforcement agencies in 2012-13, according to the latest report published by the Attorney-General’s Department.

SMH