A "sophisticated internet fraud syndicate" has been uncovered in Zambia, leading to the arrest of 77 people, including 22 Chinese nationals.
It was a "significant breakthrough in the fight against cybercrime", the authorities said after a multi-agency raid on a Chinese-run company.
The firm employed Zambians who believed they were to be call-centre agents.
Among equipment seized were devices allowing callers to disguise their location and thousands of Sim cards.
Golden Top Support Services, the company at the centre of the raid, has not commented on the allegations.
The swoop on its premises, located in Roma, an upmarket suburb of the capital, Lusaka, was led by the Drug Enforcement Commission (DEC) and also involved the police, the immigration department and anti-terrorism unit.
It came after months of intelligence gathering by the agencies following an alarming rise in internet fraud cases in Zambia, DEC director general Nason Banda said after Tuesday's raid.
He said Golden Top Support Services had recruited " unsuspecting" Zambians aged between 20 and 25.
They had been tasked "with engaging in deceptive conversations with unsuspecting mobile users across various platforms such as WhatsApp, Telegram, chatrooms and others, using scripted dialogues".
During the operation 11 Sim boxes were found - these are devices that can route calls in a way that bypasses legitimate phone networks.
This enables them to be used "for fraudulent activities, including internet fraud and online scams", Mr Banda said.
More than 13,000 Sim cards - both domestic and international - were also seized, which underscored "the extent of the operation's reach", the DEC head said.
An increasing number of Zambians were losing money from their bank accounts through money-laundering schemes, though this scam's alleged "illicit operations extended beyond Zambia's borders", he said.
Evidence indicated people in countries including Singapore, Peru, the United Arab Emirates (UAE) and others across Africa had been targeted.
Two firearms and about 78 rounds of ammunition were confiscated and two vehicles, belonging to a Chinese national linked to the business, have been impounded.
Mr Banda said the Zambian nationals had been charged and released on bail so they could help the authorities with their investigations.
The foreign nationals - 22 Chinese men and a Cameroonian - remain in custody.