A Tongan MP, Akilisi Pohiva, says the Prison Department is being uncivilised in sentencing teenage lawbreakers to an uninhabited island.
The Matangi Tonga magazine has reported up to 50 children between the ages of 14 and 16 have been kept on Ata island, an hour's boat ride from Tongatapu.
The children were unsupervised on the island and only allowed on Tongatapu once a month, to visit family and go to church.
Mr Pohiva says the governmnent should make it a priority to provide prison facilities for children on Tongatapu.
He says taking children to Ata island will not help rehabiliate them.
"I don't think it is appropriate....it is uncivilised to isolate young people ....we must give them a chance to improve their attitudes and behaviour but we can only do that when they are in a place where there are people to look after them."
Akilisi Pohiva says not many people know about the scheme but he says he is planning to publicise it.