The Vanuatu government says the Union of Moderate Parties, or UMP, was dumped from the ruling coalition last week because it was planning to unseat the Vanuaaku Pati of the prime minister, Edward Natapei.
The prime minister's spokesman, Daniel Bangtor, says the ousting was timely.
Mr Natapei dumped the UMP and replaced it with the National United Party, the Greens and independents.
Mr Bangtor says it became obvious last week that the UMP was trying to forge a coalition with the same parties, so the prime minister acted.
He says Mr Natapei also had other concerns about the UMP.
"A mongst them are the fact that the UMP ministers never took their jobs seriously, and one particular example is that a lot of them just didn't attend council of ministers meeting when they were supposed to be there."
The UMP is trying to bring a vote of no confidence in the new coalition but Mr Bangtor says they are sure they have the numbers.