The 41 asylum seekers whose fishing boat was intercepted by Australian authorities in the Indian Ocean and who were handed over to the Sri Lankan Navy, had their asylum claims assessed on the high seas via teleconference on board an Australian government ship.

The unprecedented "at-sea" assessments have been criticised by international lawyers and the United Nations as a superficial and unfair process, but defended by the government as upholding Australia’s legal obligations.

Reportedly assessed by being asked four questions, all but one of the 41 were ruled not to be refugees.

The one found to raise protection obligations decided instead to return to Sri Lanka rather than be sent to Manus Island.

In a further example of technology trouncing geography, at 2.15pm Tuesday, the High Court will hear a case regarding the fate of 153 further asylum seekers believed to be in the custody at sea of another Australian government ship.

The judge hearing the case, Justice Susan Crennan, will sit in Melbourne.

Appearing before her for the asylum seekers will be barrister Ron Merkel, QC. But the asylum seekers' solicitor, George Newhouse, will appear from Sydney.

The lawyers will communicate by video link.

Even as the case commences, the location of the asylum seekers, and in whose custody they are, is not known to the Australian public.

The High Court’s temporary injunction stopping Australia from returning the asylum seekers to Sri Lanka expires at 4pm on Tuesday.