Six Chinese nationals were arrested for using Thailand as a base for an online gambling racket during a raid on two luxury houses in San Sai district of Chiang Mai.

The raids followed a tip-off from Chinese authorities. A combined force from Provincial Police Region 5, the Tourist Police Bureau and Immigration searched the two houses at The Regent 1 housing estate in tambon San Sai Noi on Wednesday.

Three Chinese nationals, two women and one man, were detained at the first house after an online gambling setup was found there, Pol Maj Gen Surachate Hakparn, deputy chief of the TPB, told a media briefing. Seized items included two desktop computers, two notebook computers, two iPads, four mobile phones and a 225-page account book with betting details. 

The suspects - Ms Li Yujia, 29, Ms Yang Siyu, 32 and Mr Cai Di, 34 - were found accepting bets online when police entered a room on the second floor of the house.

The police team then raided a nearby house and arrested three more Chinese nationals and seized evidence of online gambling. The trio were identified as Mr Zhang Hao, 24, Mr He Pengcheng, 27 and Mr Zhao Wantong, 19. Seized from the house were a desktop computer, 5 iPads, 7 mobile phones, one set of documents and an internet service router.

All suspects were charged with colluding in operating an online gambling service and persuading people, directly or indirectly, to place bets.

Two Thais who leased the houses to the Chinese were also detained. The couple, Thitirat Phumprapayong and Chattida Yorsanon, were charged with sheltering foreign nationals without notifying immigration officials - a TM 30 violation.

The raid came after Chinese police sought assistance from the Royal Thai Police Office technology crime suppression centre in arresting a group of Chinese nationals using Thailand as a base for an online gambling operation, Pol Maj Gen Surachate said.

Investigators found out the Chinese had rented two houses in Chiang Mai and their activities raised suspicions. They mostly stayed indoors, only occasionally sending someone out to buy supplies. The investigators later confirmed they were running a gambling operation from the two houses.

Their punters mostly placed bets on online Chinese gambling card games. More than 2.5 million yuan, about 10 million baht, was found to be circulating through their system.

One of two luxury houses in Chiang Mai's San Sai district rented by six Chinese nationals caught operating an online gambling network.