The branch of the Australian Federal Police has also sought legal advice about one criminal matter where the data accessed may have been used in a prosecution, as well as a separate missing person case.

"ACT Policing has sought legal advice regarding the management of two matters relating to a missing persons case and a criminal matter where the data in question may have been used in a prosecution," the statement said.

Of the 3249 requests made without proper authorisation, 240 "generated information that was of value in progressing ongoing investigations and inquiries".

It brings the total number of unauthorised metadata requests to 3365.

ACT Policing said once the requests were identified they were referred to a case officer to ensure the information was quarantined and not used further.

President of the ACT Law Society Chris Donohue said the breaches caused problems for the administration of justice.

"If it's established the data was obtained without authorisation, or illegally, then potentially the information would not be admissible in proceedings," he said.

"If some unauthorised information was the starting point of a line of inquiry then it's quite possible the whole chain of evidence from that could be inadmissible."

Mr Donohue said the public trusted and expected police to use their powers properly, and incidents like this could cause the public to lose confidence in the rule of law.

"There's no way that this kind of scenario is to the advantage of the legal system of a whole and it is of concern that these breaches have occurred," he said

"Even if the breach was brought about inadvertently, it's still a breach and it strikes at the administration of justice, and that's what lawyers want to see done correctly."

Earlier this week a Commonwealth Ombudsman report revealed ACT Policing had accessed metadata without proper authorisation more than 100 times between October 13-26, 2015, because no one in the organisation had the correct authorisation.

Now ACT Policing has conceded the problem occurred from March 11 to October 13 as well.

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Metadata includes information like the time of phone calls and text messages and who they are to, it also includes who a phone number is registered to and can include location information.

On Friday afternoon ACT Policing revealed the problem was much more widespread than first thought, because the Commonwealth Ombudsman had only examined a two-week sample period.

None of the information related to finding a journalist's source, the statement said.

ACT Policing has said in a statement the problem occurred due to "administrative oversight" and that the problem had been self-reported to the Ombudsman.

Measures have also been put in place to ensure the issue doesn't happen again.

The ACT Greens have also labelled the breaches concerning.

"Metadata retention is a complex area that impacts all of us. ACT residents value their privacy and would rightly feel uncomfortable if authorities are accessing data inappropriately," Greens MLA Caroline Le Couteur said.