Police in Hanoi have arrested a man who has confessed to having duped Facebook users into believing he had a large cache of counterfeit currency.

Ha Van Lam, 25, admitted that he set up a Facebook account to advertise his phony business last November. Lam told interested parties that he'd send them 2.5 times the real currency they wired to his bank account in fake notes.

The mobile phone trader demanded a minimum of VND500,000 (US$22) to do business, but police say he never had counterfeit bills to send back.

A number of people sent Lam money and never heard from him again, according to investigators.