Police on Saturday said they had arrested 11 people who allegedly used Hong Kong as a base for phone scams involving the impersonation of customer service officers.

The force claims the suspects, who include six Malaysian nationals, are linked to a transnational syndicate responsible for the theft of HK$61 million in over 400 scams since April.

The arrests came after officers raided four offices in San Po Kong and Kowloon Bay.

The suspects, aged between 20 and 67, are accused of conspiracy to defraud, using false instruments, and money laundering.

The locals were allegedly responsible for duties, such as renting the centres and providing the syndicate with a large number of local prepaid SIM cards.

The force seized 87 model-pool devices,15 computers and over 80,000 prepaid SIM cards in the raids.

Chief Inspector Lee Chun-man of the Cyber Security and Technology Crime Bureau said surveillance cameras had been installed in the centres.

"It is believed the cameras allowed senior members of the syndicate to monitor the operation, as well as the workers' performance," he said.

Lee pointed out that the Malaysian suspects came to Hong Kong as tourists, and were paid around HK$10,000 to HK$16,000 each month.

"Apart from being responsible for using falsified identification documents or travel documents to register SIM cards, their duties also included managing the modem-pool devices by changing SIM cards in the devices around the clock, so as to ensure that the telecommunication network could be operated 24 hours a day," he said.

Lee also said that between May and August this year, three of the Malaysian suspects had allegedly made use of computer software to modify their passports and the ID cards of others, so as to complete the real-name registration for at least 300 SIM cards.