Gambling is illegal in the Muslim-majority archipelago, with punishments extended to bookmakers, punters and those who promote gambling content online.

Police raided a building in Jakarta on Thursday, where they found and detained 321 foreigners and seized phones, passports, laptops and computers.

The majority of those detained, 228 people, were Vietnamese nationals. The group also included 57 from China, 11 from Laos, five from Thailand and three each from Cambodia and Malaysia, police official Wira Satya Triputra told a news conference.

Some 275 people face charges of gambling and money laundering, Wira said, adding that authorities were still investigating the rest.

“We caught the perpetrators red-handed, meaning they were conducting an online gambling operation,” he said.

Preliminary investigations suggested that the ring, which started operations about two months ago, targeted victims outside Indonesia, Wira said, without specifying where.

Police have previously said that many scammers had moved operations to Indonesia and other Southeast Asian countries following a crackdown in China.

Elsewhere in Indonesia this week, immigration authorities raided an apartment building in Batam, in Riau Islands province, arresting 210 foreigners suspected of running an investment scam.

In February, Police raided two villas on the resort island of Bali and arrested 39 Indian nationals for allegedly running an illegal gambling operation.

Turnover linked to online gambling reached more than 280 trillion rupiah (about US$16 billion) last year, official data showed, with more than 12 million Indonesians estimated to be engaged in the illicit activity.