JAKARTA, Indonesia — More than 300 foreign nationals were arrested in a raid on an alleged online gambling operation in the Indonesian capital, police said Saturday, in one of the country’s largest crackdowns on illegal digital betting networks.

The 321 foreigners, mainly from Vietnam, were arrested at a commercial building near the city’s Chinatown section that investigators described as a hub for more than 70 online gambling websites, targeting players outside Indonesia, based on marketing records and digital evidence collected during the raid.

Those arrested include 228 Vietnamese, 57 Chinese and the rest came from Laos, Myanmar, Thailand, Malaysia and Cambodia, said Wira Satya Triputra, the director of general crimes with the Indonesian National Police. He said investigators were still tracing the organizers and financial backers behind the network.

“We arrested the suspects in the act while they were carrying out activities related to online gambling,” Triputra told a news conference Saturday. He said the operation was organized in a structured manner, with workers assigned to roles such as customer service, telemarketing and financial administration. Police estimate the operation had been running for about two months.

Authorities said many gambling syndicates move their operations frequently to evade detection, often recruiting foreign workers to run websites and customer services.

Triputra said many of the suspects entered Indonesia using short-term visitor visas and overstayed their permits while working at the operation, and that “immigration violations were uncovered in addition to suspected gambling and money-laundering offenses.”

Police seized cash in multiple currencies, computers, mobile phones, passports and other equipment believed to have been used to manage the gambling sites. Authorities believe the group operated at least 75 betting platforms.

As of Saturday, 275 of those detained had been formally named as suspects, while others remained under questioning, Triputra said. Those charged could face up to nine years in prison under Indonesia’s criminal and immigration laws and a fine of 2 billion rupiah ($116,000).

Similar transnational crime operations have been uncovered in recent months in Surabaya, Bali and Batam, highlighting the need for tighter coordination among law enforcement and government agencies to combat online gambling and related scams, said Untung Widyatmoko, secretary of Indonesia’s Interpol bureau.

He said authorities have detected signs that online gambling operators previously based in Cambodia are relocating operations to other countries, including Indonesia, after authorities there cracked down.

“After enforcement measures in Cambodia, we started to see a shift toward Indonesia, and that was something we anticipated,” Widyatmoko said.

Online gambling is illegal in Indonesia, the world’s most populous Muslim-majority country, which has stepped up enforcement amid concerns over organized crime and cross-border cyber operations. Police said the investigation could lead to additional arrests tied to international networks.