The sites handled more than NT$100m ($3.2m) in wagers per month, offering betting on professional baseball in Taiwan, Japan and the US, alongside international soccer, basketball, tennis and motorsports.

A total of NT$2.89m and 100,000 yuan ($15,000) was seized during the raids across 15 locations. In addition to the cash, 73 computers, 63 mobile phones and 10 servers were taken in as evidence.

The Criminal Investigation Bureau arrested a 42-year-old man, surname Wang, who had allegedly set up the betting sites and registered them as information technology companies.

An examination of the seized assets revealed Wang and his friend placed the main servers in Hong Kong and the Philippines to evade detection.

Unit Captain Chen Chieg-Chang said: “We have evidence Wang is the main financial backer for the illegal gambling business.

“He got a friend, a man surnamed Hsiao, to register several information technology start-ups last year, but these were shell entities to cover the operations of the online gambling sites.”

The 43 people arrested are currently being held for questioning.