A committee of 35 losing candidates from Vanuatu's Port Vila constituency has announced plans to launch a petition against the results of Tuesday's general election in the capital and the Efate rural constituency.
The group says at least 6,000 voters in and around the capital were denied the chance to vote because their electoral cards were not properly registered by officials.
The committee says the problems had a big impact on the election outcome, and it is demanding a by-election.
A spokesperson, Hilda Lini, says its petition is based on what was happening in Port Vila and Efate but is reflective of a country-wide pattern that happens each election.
"The way electoral cards have been prepared and recorded in the electoral roll which seems to be very unorganised. People turn up to vote and their names are not on the electoral roll even though they have cards."
The political party of the caretaker Prime Minister, Sato Kilman, says it will lodge election petitions in four constituencies.
The People's Progressive Party chief executive officer Dick Tete told the Daily Post newspaper that the party suspects fraudulent practices around the election process in Ambae, Port Vila, Tanna and Mr Kilman's own constituency, Malekula.
In unofficial election results to date, the PPP has won six of the 52 seats in parliament.