A stellar cast of border-protection heavyweights will face a grilling over the federal government's asylum seeker boat crackdown secrecy.
Operation Sovereign Borders commander Angus Campbell, Chief of the Defence Force David Hurley, Customs boss Michael Pezzullo as well as Defence and Immigration department secretaries Dennis Richardson and Martin Bowles are scheduled to give evidence at a Canberra hearing on Friday.
A Senate committee is examining the government's reliance on "public interest immunity" to deny the upper house access to official documents.
The Senate has demanded the government disclose specific details about "operational matters" related to asylum seeker boat interceptions.
In response the government tabled transcripts of the minister's media briefings, citing national security reasons for keeping other information under wraps.
Assistant Immigration Minister Michaelia Cash was invited to attend the hearing, but her office told AAP she had a prior commitment.
Clerk of the Senate Rosemary Laing will also front the inquiry.