The syndicate, who ran their operation from abroad to avoid detection by Chinese officials but did not target any victims in their host country, made around six trillion rupiah ($450 million) since beginning operations at the end of 2016, Indonesia police said. 

They were arrested following a tip-off from Chinese authorities.

"We are conducting an intensive investigation and currently coordinating with the Chinese police to deport them," said national police spokesman Rikwanto, who goes by one name.

The group, based in several locations across Indonesia, contacted victims pretending to be Chinese police or law officials, promising to help resolve their legal cases in return for immediate cash transfers, Jakarta police said. 

The criminal network included IT specialists who would retrieve information on victims and develop communications systems for contacting them, he said.

Chinese nationals were arrested in Jakarta, the city of Surabaya and on the resort island of Bali in separate raids over the weekend. 

"The perpetrators and the victims are Chinese. It just happens that they operate from Indonesia," said Jakarta police spokesman Argo Yuwono.

Police are investigating how several of the Chinese suspects were able to enter the archipelago without a valid passport.

Cyber criminals targeting victims in China have increasingly exploited technological advances to operate from abroad, spreading across Southeast Asia and beyond in recent years.

China has become increasingly assertive in extraditing suspects.