Fiji's Vice-President Jope Seniloli has been jailed for four years, after being found guilty of involvement in a coup against a previous government.
Seniloli's lawyer pledged to appeal the verdict
The High Court on Thursday found Seniloli guilty of helping George Speight oust Fiji's first Indian prime minister, Mahendra Chaudhry, in 2000.
Seniloli had unlawfully sworn in ministers in Speight's administration, and faced up to eight years in jail.
Four other men convicted with him have also been given prison terms.
Deputy Speaker Rakuita Vakalalabure and three businessmen were jailed for between six years and 12 months, after being convicted on the same charges.
A sixth defendant, Sports Minister Sireli Leweniqila, was acquitted of the charge.
Announcing the verdict, High Court Judge Nazhad Shameem said there were "elements of betrayal" in the actions of the accused.
Seniloli's lawyer Maqbool Raza said he was "appalled" by the sentence and planned to appeal, according to Reuters news agency.
Before sentencing, the police had issued an appeal for calm.
"Police will also arrest anyone who will be involved in any illegal activity such as marches or protests because we have not
issued any permits to anyone," police spokesman Mesake Koroi said.
Seniloli - who was the most senior figure to be implicated in the uprising of May 2000 - will now be stripped of his post.
The rebellion, by a small number of gunmen led by the indigenous Fijian George Speight, ousted ethnic Indian Mahendra Chaudhry.
Mr Chaudhry's cabinet and lawmakers from his Fiji Labour Party were held at gunpoint for 56 days inside the parliament compound in Suva.
The High Court also said Seniloli took an unlawful oath to become president while the incumbent, Ratu Sir Kamisese Mara, was still in office.
Martial law was put in place in the aftermath of the coup, and George Speight was eventually arrested. He is now serving a life sentence after being convicted as a traitor.
An interim government was installed under Laisenia Qarase, who has since been democratically elected as Fiji's prime minister.
Despite his links with the coup plotters, Seniloli was sworn in as vice president.
Correspondents said at the time that his appointment illustrated how Fijian nationalism has prospered since the uprising.
Mr Qarase has been determined to enhance the political and economic power of the indigenous community, which has sometimes come at the expense of the large ethnic Indian minority.
Racial tensions are never far from the surface in Fiji, where the indigenous population resents the economic prosperity of the Indian community, which was originally brought to the Pacific island to work on British colonial sugar cane farms.