"We have a crisis here," Mahendra Chaudhry, the opposition Fiji Labour party leader, said on Monday after learning that three Labour MPs would not be given their choice of ministries.
The party later said its MPs would meet to discuss the matter on Tuesday - when the indigenous Fijian-dominated Soqosoqo Duavata ni Lewenivanua (SDL) party ministers are to be sworn in by Ratu Josefa Iloilo, the president.
This was seen by observers as an effective boycott of the ceremony.
Chaudhry, who informed Laisenia Qarase, the prime minister, of the decision by letter, earlier said that his Indo-Fijian-dominated party might now refuse to join the SDL in a multiparty cabinet.
Fiji's constitution was redrafted in 1997 to reduce the South Pacific nation's racial divide by ensuring that Labour and SDL would both be entitled to seats in the cabinet. Any party with more than seven seats in the 71-seat parliament is entitled to a ministry.
Labour refused to join the cabinet when Chaudhry lost to Qarase in general elections in 2001, a year after Chaudhry was deposed as the country's first ethnic-Indian prime minister in a coup by armed Fijian nationalists.
But Chaudhry agreed to form a joint cabinet after Qarase was narrowly re-elected this month.
Qarase was narrowly re-elected
in polls from May 6 to13
It would have been the first time in Fiji's history that a large opposition party had joined a cabinet.
Fiji has had three coups since 1987. Observers believe that a multiparty cabinet would ease fears of another coup by removing the justification for Commodore Frank Bainimarama, the military chief, to move against Qarase, whom he accuses of racism.
Qarase says he is opposed to the concept of a multiparty cabinet but intended to form one "because it is the law".
He accepted Labour's list of nine MPs to be included in his 22-member cabinet, but did not give three of them the portfolios they wanted.
"The final decision is mine," Qarase said.
Chaudhry, who chose to remain leader of the parliamentary opposition rather than ask for a cabinet place for himself, accused Qarase of carrying out "another manipulation of the process ... to frustrate the establishment of a multiparty cabinet once more".
Racially divided Fiji has had
three elections since 1987
Earlier on Monday, Qarase gave no hint of the difficulties.
Asked whether Chaudhry had agreed with the cabinet posts, Qarase said: "He has given me a list ... and I have made a decision".
Chaudhry accused the prime minister of refusing to work in a co-operative relationship as the law required, saying Qarase had instead adopted a "master-servant attitude".
"Saying I'm the boss ... is not in the spirit of power sharing under the constitution," Chaudhry said.