Peter Dutton must accept responsibility and come clean about his illegal detention of at least two Australian citizens, Greens Immigration spokesperson Nick McKim says.

"Peter Dutton wrongfully robbed these Australians of their freedom," Senator McKim said.

"He is running an offshore detention regime that has deprived thousands of refugees and asylum seekers of their liberty and deliberately harmed men, women and children."

"Whether through incompetence or design, the focus of Peter Dutton's cruel regime has now been trained on Australian citizens."