Australian Immigration authorities have been criticised for secretly sending five Papuan asylum seekers back to Papua New Guinea after intercepting their boat at Saibai Island last month.
The government hadn't revealed any details of the case until questioned by The Australian newspaper.
A spokeswoman for Immigration Minister said the arrival was not announced because it was a routine operational matter.
The Papuans had raised protection issues but were reportedly unable to apply for protection because Saibai Island is excised under Australia's Migration Act.
The five Indonesian nationals have already been sent back to PNG, where they had been living before their voyage.
A refugee and immigration lawyer David Manne says the Australian immigration's handling of the case is of concern.
"There's a very serious question about whether there has been a circumvention of the very requirement to properly assess the protection needs of an asylum seeker in Australian territory, and as part of that to determine whether they are a refugee and if they are, to ensure that they're not sent back to a situation which is unsafe."