Among the three foreigners are two Vietnamese nationals and a French national.
Despite not meeting a requirement to spend ten years in Vanuatu, they were granted Vanuatu citizenship by naturalisation.
This month opposition leader Ralph Regenvanu told local media the opposition was aware of about ten cases of illegally-granted Vanuatu citizenship under naturalisation by the office.
The director of passport and immigration, Jeffrey Markson, denies that the citizenship programme has breached rules.
