Fiji Prime Minister Laisenia Qarase says he is under house arrest after heavily armed troops have surrounded his Suva residence for much of today.
He has refused to resign and says what happens next is anyone's guess.
Mr Qarase told Reuters he would not resign and would have to be forcibly removed from office.
He says he is the democratically elected prime minister of the people of Fiji.
Fiji's President Ratu Josefa Iloilo said in a statement that he did not support the military's action.
President Iloilo said he neither condones nor supports the actions of the military today, which he went on to say were clearly outside the constitution, and contrary to the country's laws and democratic ideals.
He called on the military to find a solution to the political crisis within the law and asked Fijians to pray for their country.
Fiji media and New Zealand Prime Minister Helen Clark said earlier the president had reportedly dissolved parliament and sanctioned Mr Qarase's removal.
Miss Clark criticised the president's action and immediately imposed sanctions against Fiji's military.