Vanuatu's transnational crime unit says it wants to establish how many fake euro notes have been put into circulation.
The existence of such counterfeit notes became public after a Vanuatu delegate to the climate conference in Copenhagen was found with fake euro notes.
He said he had obtained the notes from a money exchange in Port Vila shortly before flying to Denmark.
The team leader of the unit, Wilson Abiut, says they have spoken to witnesses and are following some leads.
But he says the investigation is still in its early stages.
"It's very important to establish an exact idea of how many counterfeit euro notes are in circulation in Vanuatu, that's the purpose of the investgation; to identify and know the quantity of the fake euro notes."