The operation was shrouded in secrecy, with authorities refusing to confirm that the process was under way. It was confirmed by sources on Nauru.

Also on Friday, the Immigration Department transferred the second group of asylum seekers to Papua New Guinea's remote Manus Island. The department said eight families were sent to the island, 16 adults and 12 children from Sri Lanka and Iran.

There are now 31 adults and 16 children on Manus Island. The first transfer was on September 21.

Hunger strikes have now spread to Manus, with reports that seven people in two families were on their third day of hunger strike on Friday. One of the families is an Iranian couple and their 18-year-old daughter. One of the asylum seekers said the protest started after the group was told it could take four to six years for their claims for asylum to be processed.

Images released by the department show a mixture of tents and buildings on Manus. The tents have army-style stretchers inside.

Eight Save the Children staff are providing education for the children on the island. Programs director Scott Gilbert said staff would teach the children basic pidgin and English, in the hope of having them attend the local PNG school.

The conditions were ''basic'', he said, and only just acceptable. ''But for children as vulnerable as this, we would like to see the conditions improve more.''

The Immigration Department said that after the asylum seekers arrived, they went through immigration clearance, before being moved into the centre.

''The completion of this transfer reaffirms the strong message of deterrence for anyone considering risking their lives on dangerous people smuggling boats,'' the department said. ''There will be no advantage for boat arrivals.''

It said the asylum seekers sent to Manus Island were chosen ''based on operational considerations and an assessment of their particular circumstances to confirm transfer was appropriate''.