Cambodia says it has extradited to China a billionaire businessman accused of masterminding a vast cryptocurrency scam in which trafficked workers were lured to forced labour camps to defraud victims globally.

Chen Zhi was among three Chinese nationals arrested on 6 January after a joint investigation into transnational crime lasting several months, Cambodia said.

The US charged the 37-year-old last October with running internet scams from Cambodia that it said had stolen billions in cryptocurrency. The UK also sanctioned his global business empire, Prince Group.

Cambodian authorities have also suspended the operations of Prince Bank, a subsidiary of Prince Group. The bank has been placed under liquidation and banned from offering new banking services - though customers can still withdraw money and repay loans, the National Bank of Cambodia said on Thursday.

Last year, US authorities seized about $15bn worth of bitcoin that alleged belonged to Chen, in what FBI Director Kash Patel described as one of the largest financial fraud takedowns in history.

Since Chen Zhi was indicted by the US on fraud and money-laundering charges in October, his whereabouts have been unclear. But on Wednesday, the Cambodian authorities stated they had arrested three Chinese nationals namely Chen Zhi, Xu Ji Liang, and Shao Ji Hui and extradited them to the People's Republic of China.

The UN estimates that hundreds of thousands of people have been trafficked to South East Asia, many in Cambodia, lured by the promise of legitimate jobs and then forced to run online scams.

Chinese authorities have also been quietly investigating the Prince Group since at least 2020, describing it as a major transnational online gambling syndicate based in Cambodia. The company is accused of running online fraud schemes in a number of court cases.

Cambodia's ruling elite have been close to Chen Zhi for years. The government has said little since the US and UK sanctioned Prince Group, apart from urging US and UK authorities to ensure they had sufficient evidence for their allegations.

By some estimates, scam businesses may account for around half of the entire Cambodian economy.