Philippine authorities arrested around 100 people on Friday in a raid on a suspected online scam farm in Manila they said extorted victims.

The raid in the Makati financial district was part of a crackdown against online crime operators that often act under the guise of gaming firms.

Agents from the Presidential Anti-Organised Crime Commission (PAOCC) and the National Bureau of Investigation, armed with assault rifles, surrounded two offices of a lending agency and arrested the suspects as they worked side-by-side at computers.

The suspects, many of them young Filipinos, allegedly sought out victims via TikTok and other social media, offering collateral-free loans of up to 25,000 pesos ($428).

Borrowers were charged 35 percent weekly interest and those who fell behind on payments were harassed, humiliated and threatened with having their personal information spread online, PAOCC director Gilberto Cruz told reporters at the scene.

"Some of those they harassed developed mental problems, others fell into depression, and there have even been some suicide incidents that occurred because of the harassment perpetrated by these people," Cruz said.

The suspects could be charged with fraud and other violations under the country's cybercrime laws, he added.

The raided company, Wewill Tech Corp., required victims to provide personal information and family photographs, which the scammers then used for threats, according to Cruz.

Some victims of similar scams have reported having coffins and funeral wreaths delivered to their homes, he said.

Authorities are checking the nationality of the owners, Cruz said, adding that they had arrested Chinese suspects running similar operations in the past.

The scam farm owners are suspected to be remnants of online gaming operators that were banned under orders of President Ferdinand Marcos last year, he said.

"Most of their keyboard workers are Filipino" and communicated with victims in the local language, Cruz told reporters.

"What is frightening here is it is Filipinos who are harassing and defrauding their fellow Filipinos," he said.

The United Nations Office on Drugs and Crime has tagged Southeast Asia as "ground zero" of global scamming operations that the authorities say are run mainly by Chinese-origin crime organisations.