The Federal Government has admitted it has possession of a secret anthropological report which provides the foundation and sole basis for the nomination of Muckaty Station, near Tennant Creek, as the most likely site for a radioactive waste dump.

Last week Resources Minister Ferguson insisted that neither he nor his office ‘are or had ever been in possession of an anthropological report commissioned by the Northern Land Council' and supplied to then Minister Julie Bishop in 2007.

"Today we saw Minister Kim Carr backflip and admit that Martin Ferguson has the report, but that it won't be put in the public domain," said Greens Senator Scott Ludlam.

"This government cannot on the one hand claim the previous process was corrupt and a sham, and on the other continue to withhold the very piece of evidence that the Muckaty nomination rests on. The report should be tabled immediately.

"The Muckaty nomination should be scrapped and a new transparent process set in motion," Senator Ludlam said.