The founding members of the FijiFirst party, including former prime minister Frank Bainimarama and ex-attorney-general Aiyaz Sayed-Khaiyum, have resigned.
Sayed-Khaiyum confimed that party president Ratu Joji Satalaka, vice President Selai Adimaitoga, acting general secretary Faiyaz Koya and treasurer Hem Chand have also resigned from the party, according to local media reports.
Sayed-Khaiyum said the other vice president Ravindran Nair and founding member Salesh Kumar have also resigned.
He said the resignation letters were given to the Registrar of Political Parties last Friday, 7 June.
One FijiFirst MP, Ketal Lal, posted on Facebook: "Sad day for Fiji" after the news was made public.
Dialogue Fiji executive director Nilesh Lal said the "mass resignation of founding members and senior officials is probably one of the most ill conceived moves on the part of the founding members of the FijiFirst party".
Lal said the move will "severely weaken" the position of the two minor parties - Sodelpa and NFP - in the coalition government.
"It was always in the interests of NFP and Sodelpa that FijiFirst remained a strong, united and viable party, and with this latest development, this is clearly not the case any longer. Both Sodelpa and NFP lose their bargaining chip, with the demise of FijiFirst."
RNZ Pacific has contacted the Registrar of Political Parties, Ana Mataiciwa, for comment.
Last week, FijiFirst confirmed that it had sacked 17 MPs after they voted for a pay rise - going against a party directive.
However, the expelled Fijifirst MPs said they were going to contest the decision and would remain parliamentary opposition, highlighting divisions within the largest single party in the Fijian Parliament.
Mataiciwa, who was also the supervisor of elections, said FijiFirst needed to amend its consitution by 28 June or risk deregistration.
She told local media the party's constitution did not have guidelines on how internal party disputes were resolved, which was in breach of the Political Parties (Registration, Conduct, Funding and Disclosures) Act 2013.