Human rights investigators from the United Nations have been been forced to cancel a trip to Nauru to investigate the fate of asylum seekers sent there by Australia.
The order to stand down came from the Nauru government but is understood to have originated in Australia, which pays many of the near-bankrupt island nation's bills.
The order to stay away was given as the group was about to depart for the Pacific Island after a two-week visit to New Zealand looking at polices on detaining prisoners.
Its next port of call was to have been Nauru but the trip has been called unsuitable, and cancelled.
Canberra started sending asylum seekers to Nauru in 2001, to deter other asylum seekers from trying to get into Australia.
Conditions in the camps, in which several hundred people are living, have been criticised repeatedly.
"The government of Nauru, which invited us, have asked us not to come," the group's leader, Mads Andernas, said.
"They cite practical reasons for it not being suitable or practical for us to come."
Mr Andernas declined to comment on the conditions on the island without being able to go there.
A spokesperson for the rights organisation Amnesty International, Graeme McGregor, says the conditions at Nauru are harsh, and are being kept secret.
"This is just another denial of transparency in a string of denials. Although the Australian people are paying billions of dollars for this policy they're not getting to see what's actually going on in there."