Police in Vietnam have busted an illegal gambling ring linked to Asian online betting operator Dafabet.

On Tuesday, Vietnamese media reported that the Ministry of Public Security’s Cyber Crime Prevention Police Sector had detained four individuals in Ho Chi Minh City connected with an illegal betting ring linked to the Philippines-licensed Dafabet.

While three of the detained individuals are Vietnamese nationals, the suspected ringleader of the gang is a 31-year-old Singaporean named Wong Boon Leong. Police say Leong entered Vietnam in 2013 and began setting up an illegal sports betting operation that ultimately built a client list of thousands of Vietnamese bettors, who wagered around VND 1t (US $45m) with the ring.

Police didn’t specify what led them to uncover Leong’s operation, but a raid on his Ho Chi Minh City flat turned up betting-related documents and invoices, as well as an array of electronic equipment used to facilitate money transfers to and from the Philippines.