WA Police have collected the metadata of at least one journalist without a valid warrant, a Commonwealth Ombudsman report has revealed.

A Commowealth Ombudsman's report has revealed WA Police had twice obtained the metadata of at least one journalist without a valid warrant. Credit: Reuters

Along with one instance of the Australian Federal Police accessing the telecommunications data of a journalist without obtaining a warrant, the report revealed WA Police had sought warrants from a person who was not authorised to issue one.

"This occurred due to a lack of awareness by WA Police regarding to whom an application for a Journalist Information Warrant could be made," the report tabled in Federal Parliament said.

"In response to this issue, WA Police took steps to quarantine all information obtained under the invalid warrants."