The Commonwealth Secretary-General, Don McKinnon, says there are no signs Fiji will soon return to parliamentary democracy.
Fiji was suspended from the Commonwealth in December in the days following the takeover.
Military commander Frank Bainimarama said last month fresh elections in the Pacific island nation were at least three years away.
However, Mr McKinnon has blasted the coup leader's "unsatisfactory" timetable and insisted he would keep up dialogue, certain that democracy would eventually prevail and Fiji would return to the Commonwealth fold.
He told AFP that the situation is very sad and it should not have happened.
Commodore Bainimarama led the military coup in December, accusing prime minister Laisenia Qarase's government of corruption and of favouring the indigenous majority over the ethnic Indian minority.
Mr McKinnon says there was no reason in Fiji for a military leader to decide to take over the government.
He says even if if there was corruption identified and highlighted, that is no reason as there are the political and judicial systems to deal with that.
He says if people do not like a government, they can vote a government out.