The government's improper management of Australian Border Force's statutory powers is squarely the fault of Immigration Minister Peter Dutton.

"This government has grabbed for itself a massive range of new powers in its process of militarising the Department of Immigration and Border Protection," Greens Immigration spokesperson Senator Nick McKim said.

"The failure of the Department to ensure that these powers are being used legally falls squarely on the shoulders of the incompetent Peter Dutton."