Two men believed to be ringleaders of a large-scale phone scam based in Thailand were arrested Thursday in Japan, bringing the total number of those arrested in the case to 28.

Kengo Yasutake, 36, and Shimpei Hirata, 34, are suspected of sending instructions to a rented luxury house located in the Thai beach resort city of Pattaya, where a separate group of Japanese men had called people across Japan claiming they had failed to pay subscription fees for a website.

The group is believed to have tricked over 200 people out of more than ¥200 million ($1.8 million) in total. Fifteen Japanese men in their 20s to 50s were arrested by Thai police last March and Japanese investigators arrested them in May aboard aircraft while they were being transported from Thailand to Japan.

Members of the group had various roles, such as making phone calls, cashing swindled electronic gift cards in Japan, as well as managing the scam operation site, according to investigative sources.

They were arrested on suspicion of scamming a woman living in the city of Fukui, and two others by alleging in an email sent to them last March that they had failed to pay website subscription fees, and making them purchase electronic gift cards worth a total ¥780,000.