Former New Zealand Governor General Sir Paul Reeves warns Fiji will pay a heavy price for ignoring the rule of law.
Sir Paul's report on Fiji's 1995 constitution resulted in the adoption in 1997 of a new constitution, which was abrogated by President Ratu Josefa Iloilo on Friday.
He later he reinstated the interim government, despite a Court of Appeal ruling on Thursday that it was illegal.
Officers from the Ministry of Information have been installed in media offices. Fiji TV pulled Sunday's 6pm news bulletin and the Sunday edition of The Fiji Times ran blank news pages with statements that stories had been censored.
Guards have also been installed outside the homes of known government critics.
Sir Paul, who's the special representative of the Commonwealth Secretary General to Fiji, says the military regime is on a slippery slope downwards.
He says the situation is likely to see Fiji's status within the Commonwealth and the Pacific Island Forum downgraded.
The military has ruled Fiji since December 2006 when the elected government was overturned. It was the fourth coup since 1987.