Eighteen people have been arrested on suspicion of providing or using forged documents for applications to Hong Kong's top talent scheme which comes with residency rights.

The Immigration Department on Wednesday said five of the 18 are Hong Kong residents suspected of running the scam operation, while the rest are mainlanders who made applications under the Top Talent Pass Scheme.

At a press briefing, the department said a syndicate used social media to contact people interested in securing Hong Kong residency, claiming they could provide a "one-stop service".

"The syndicate would first charge a fee of HK$1 million to HK$1.5 million and offer one-stop services such as forging documents relating to overseas university qualifications, student visas, immigration stamps and an employment certificate for visa applications," said Assistant Principal Immigration Officer Hui Chi-kin.

"After the applicants receive permission to enter Hong Kong, they are then charged another HK$600,000 to HK$1 million for follow-up services, which include applying for identity cards for the applicant's dependents, making housing arrangements and creating false employment and salary records."

Hui said the syndicate is thought to have been operating for 1.5 years and filed at least 22 applications, involving some HK$55 million.

The five people suspected of being part of the gang are also believed to have taken part in money laundering activities, the department said.

It added that the authorities will be stepping up checks on talent scheme applications.