Police said in a statement that Peter Conlon, who ran the online fundraising platform Ammado, has been under arrest since December 24th.
The International Federation of Red Cross and Red Crescent Societies (IFRC) said in a separate statement that it was "one of a number of non-profit organizations owed money by the online donation provider, Ammado AG".
"Ammado AG has failed to pay approximately 1.8 million Swiss francs ($1.9 million, 1.6 million euros) donated via its platform to IFRC and to a number of National Red Cross and Red Crescent Societies around the world," the Geneva-based body added in a statement.
The IFRC said it filed a criminal complaint in Switzerland against Ammado in September after several failed attempts to secure the pledged funds.
Zurich police said that Ammado's Swiss offices were raided on December 22nd and that initial evidence suggested "several million" Swiss francs in collected donations were not forwarded to the charities concerned.
Multiple Irish media reports have identified Conlon as an Irish national who also served as managing director of Pembroke Dynamic Internet Services Ltd, an Irish-registered IT firm linked to Ammado.
The Irish Charities Regulator said in a statement that it had opened its own probe "into matters relating to the online charitable donation firm Pembroke Dynamic Internet Services Ltd, which was put into liquidation by the High Court last week."
Irish media reports said the UN refugee agency was among the organizations affected, but a UNHCR spokesman was not immediately available to confirm the information when contacted by AFP.