A Dunedin man's 18-year online romance has turned out to be a half-million-dollar scam

A 44-year-old Auckland woman has been arrested today after a search of an Ellerslie property.

Police allege she defrauded the man of 525-thousand dollars over nearly two decades.

She's facing a representative charge of obtaining by deception and is due in court next Tuesday.

Acting Detective Senior Sergeant Ali Ramsay says scammers often exploit victims' trust and urges caution meeting people online or through dating apps.