The new Vanuatu prime minister, Serge Vohor, says his government will launch a constitutional application to challenge last year's change of government which saw Sato Kilman become the prime minister.
Mr Vohor, who ousted Mr Kilman in a no confidence vote last Sunday, made the announcement in response to Mr Kilman challenging last Sunday's process.
Mr Vohor now claims Mr Kilman was not elected but nominated unopposed by the then speaker, Georges Wells.
He says there was no roll call by the clerk of the parliament and Mr Kilman was not elected through secret votes as stipulated by the constitution.
In unprecedented circumstances, the media and the public were prevented from entering the parliament chamber and parliament premises by the Vanuatu Mobile Force but members of parliament witnessed what happened.