The opposition Greens party in Australia says the government has done a special deal to persuade Papua New Guinea to take in three Papuans, who should have been processed in Australia.
Greens Senator, Kerry Nettle says the men, picked up in the Torres Strait in May passed through PNG.
She says the men stayed for less than seven days and should not have been returned to PNG from Australia.
But Australian officials say the three were returned under the 2003 agreement, in which PNG agreed to re-admit from Australia any third-country nationals who had been in PNG for more than seven days, but had failed to seek asylum there.
But Kerry Nettle, who has been on a fact-finding mission in PNG, says PNG Border Affairs Director Chris Kati told her in Port Moresby that the three had been in PNG for less than seven days.
The three Papuans are now in the East Awin refugee camp in PNG's Western Province.