The Australian Greens say they will test the Senate's capacity to force the government to release documents relating to Operation Sovereign Borders.
A Senate committee is examining the government's reliance on "public interest immunity" to deny the upper house access to official documents.
Those appearing at the committee include the Immigration Minister, Operation Sovereign Borders commander, Defence Force Chief and Customs boss.
Greens Immigration spokeswoman Sarah Hanson Young says the Immigration Minister could be found to be in contempt of the Senate.
"The parliament has the responsibility to make sure that claims made by the government to keep information from the public, to keep the public in the dark must be tested.
"We've had a government who is obsessed with secrecy. That obsession is sinister and dangerous. It's putting the lives of our brave men and women at risk, it's putting the lives of vulnerable refugees at risk."