The opposition in Nauru's 19 seat parliament has been reduced to four after the sentencing of Jaden Dogireiy at the weekend.
The MP was jailed for 13 months, which automatically disqualifies him from sitting in parliament.
He had initially been acquitted but on appeal to the Supreme Court he was convicted of assault and jailed.
Dogireiy has begun serving the sentence and is yet to indicate whether he will appeal.
The parliament building in Nauru. Photo: Supplied/ @ChrisTrott