Ministers are "dragging their feet" in saying how many organisations and individuals responded to its rushed consultation on the future of the Agricultural Wages Board (AWB) in England and Wales.
Unite believes the "stalling" by Defra is designed to dilute the opposition to the abolition of the board.
Unite national officer for agriculture Julia Long said: "We have been asking officials at the Defra library, when all the consultation responses will be available for public viewing.
"We think this is very important, as not only would it allow us to actually check the content, position and number of responses, it will also enable us to check this information against the Defra summary and response when it eventually appears.
"It will also highlight those organisations that missed out due to the extremely short consultation period and this would then add weight to our legitimate complaints about the whole consultation process.
"We believe that the government is dragging its feet in the hope that that this sustained attack on some of the lowest paid workers in the country will simply disappear.
"However, Unite will continue to shine a spotlight on the government’s shameful behaviour on this issue."
The Government’s consultation ended on 12 November.
Defra minister David Heath said that the responses to the consultation will be made available "in due course".
The NFU believes the board will be abolished some time in 2013.