Brought by Victoria Legal Aid on behalf of the four plaintiffs, the interlocutory application asserts, among other things, that the decision by the Minister for Immigration and Citizenship to detain the minors on Christmas Island was made unlawfully and that there was no authority to detain them and transfer them to the Melbourne Immigration Transit Accommodation facility.

VLA's submission, which was filed in the High Court last week, states that since being detained, the condition of the plaintiffs has deteriorated to the point where they have been assessed as having severe psychological problems which necessitate release.

The VLA's primary argument is that section 4AA of the Migration Act says children should only be detained as a matter of last resort.

The High Court will be called upon to determine whether the Minister for Immigration, by detaining the minors, breached his guardianship obligations and duty of care.

Both the Department of Immigration and Citizenship and Victoria Legal Aid have declined to comment on the matter at this stage.

The hearing is set down for 9.30am tomorrow.