The Fiji Trades Union Congress says the constitution review process lacks transparency and it fears the will of the people will not be reflected in the new document.
It has condemned the pre-conditions the interim regime has placed on people wanting to sit on the Constituent Assembly, which will consider the draft constitution.
The Congress says these people have to accept the regime's non-negotiable positions on issues such as immunity and the role of the military.
But it says such preconditions would reduce the Assembly to a talk shop, rubberstamping the military's agenda.
The Congress says the regime must reconsider the process to ensure it remains credible and that the will of the people is truly enshrined in the new constitution.
It says the military must also remain subservient to an elected government to ensure there are no more coups.