This photo, provided by the National Police Agency, shows one of the suspects of a phishing scam ring being repatriated through Incheon International Airport, Sept. 14. Yonhap

Police have rounded up seven members of a Vietnam-based text message scam ring and repatriated six of them for investigation into allegations they extorted about 10 billion won ($7.5 million) from victims.

The suspects, including the smishing ring leader, were brought home last week after they were arrested through a joint investigation with Vietnamese police, the National Police Agency said. Smishing is a term coined from combining SMS and phishing and refers to tricks extorting people through text messages.

The ring is accused of extorting some 10 billion won in total, the most among such phishing scams, from 230 victims by sending text messages with links attached on the pretext of wedding invitations or parcel service, which install malicious programs that extort money once clicked on.

Police launched an investigation into the case in July last year following a report of fraud from a digital wedding invitation, and they have since arrested 86 members of the ring active in South Korea, including the seven detained in Vietnam.

The police analyzed some 300,000 transactions from nearly 70 fake bank accounts in which money was remitted and rounded up two Vietnamese affiliated with a domestic ring, and formally arrested another.

Police said they officially began cooperating with Vietnamese authorities in September last year to share intelligence information about the criminal ring and prevent further damage.

"This is an exemplary case of tearing down a criminal ring based overseas by coming together with local judicial agencies and South Korean police stationed overseas," a National Police Agency official said, vowing to continue to counter such organized crimes via cooperation between countries. (Yonhap)