Police will interview staff from Victorian Opposition Leader Daniel Andrews' office over a stolen dictaphone.
A private conversation between a Fairfax journalist and former premier Ted Baillieu recorded on the dictaphone was emailed to Liberal party members in June.
Fairfax Media reports police plan to interview staff from Mr Andrews' office about how the recordings were distributed.
Deputy Opposition Leader James Merlino said he fully supported the staff in Mr Andrews' office.
"There is currently a police investigation going on so I don't think it's appropriate for me to provide a commentary here this morning," Mr Merlino told reporters on Tuesday.
"This has been a mess from the beginning. No one knows who or how it got distributed."
When asked if Labor had spoken to police and whether it would co-operate, Mr Merlino responded: "I'm not aware and yes."
The dictaphone was left behind at a Labor party state conference in May and handed in as lost property.
Mr Andrews' chief-of-staff and Labor's state secretary were among those who listened to the tape before assistant secretary Kosmos Samaras destroyed it.
Mr Samaras admitted making copies of the dictaphone's recordings but said he later destroyed it and the files.
Mr Andrews has repeatedly said he is satisfied his staff had nothing to do with the distribution of the recording.
A spokesman for Mr Andrews said he would not comment on potential police interviews.
"As police are conducting inquiries, it would not be appropriate to provide a running commentary on this matter," he told AAP.
A spokeswoman for Victoria Police said she could not comment on an ongoing investigation.
The recording emailed to Liberal members was an off-the-record conversation in which Mr Baillieu criticised his colleagues and referred to independent MP Geoff Shaw, upper house Liberal MP Bernie Finn and his "crazy mates", and federal government minister Kevin Andrews.