HONG KONG (AP) — Hong Kong customs officials have arrested seven people linked to the territory's largest ever money laundering case, involving about 14 billion Hong Kong dollars ($1.8 billion) some of it linked to a scam case in India.

The seven local residents, aged between 23 and 74, were part of a large-scale transnational syndicate that used various shell companies and bank accounts to transfer large sums from overseas to the city under the guise of running international trading businesses, customs officials said Friday.

One account once received as much as 100 million Hong Kong dollars ($12.8 million) on a single day, they said.

Ip Tung-ching, the head of customs financial investigation bureau, said 2.9 billion Hong Kong dollars ($371 million) of the total was suspected to be linked to a scam case involving a mobile application in India. But she did not say which application it was.

Some of those arrested were non-Chinese residents of Hong Kong, she said without giving details.

Authorities believe the syndicate received remittances from India in name of exporting electronic devices, diamonds, gems and precious metals, Ip said. Proceeds were then transferred to bank accounts in Hong Kong for money laundering.

“These acts of money laundering provide protective umbrellas for the illegal profits of criminals,” she said.

Law enforcement in Hong Kong, India and elsewhere cooperated in carrying out the operation, enabling its success, Ip said.

Yu Yiu-wing, the bureau’s divisional commander, said officers exchanged intelligence with Indian authorities and found some of the money came from two jewelry companies that Indian authorities said were connected to the scam.

A 34-year-old Hong Kong resident arrested in late January is suspected to be the syndicate's mastermind, she said.

Officials have confiscated electronic devices, documents, and over 8,000 carats of suspected synthetic gem stones apparently meant for export to India.

The investigation was continuing.

The previous record money laundering case involved about 6 billion Hong Kong dollars ($767 million) and arrests of nine people in January 2023.