Hundreds of people forced to work in an online scam center in the Philippines were rescued in a raid on Thursday that also saw eight suspects arrested, according to police.

Acting on a tip from a Vietnamese man who alleged to have escaped the sprawling compound north of capital Manila, police said they unmasked an operation where suspected victims of human trafficking were forced into conducting various online scams.

"The rescued workers told us (the company) engages in love scams, romance scam, cryptocurrency scams and other scam activities," said Gilberto Cruz, executive director of the crime task force that led the pre-dawn raid.

"The victims were controlled by having their passports confiscated so they were unable to leave."

Police found 432 Chinese nationals, 371 Filipinos, 57 Vietnamese, eight Malaysians, three Taiwanese, two Indonesians and two Rwandans at the site.

The 10-hectare (25-acre) complex in Bamban was posing as an internet gaming company, according to a police statement.

Across Southeast Asia, scam centers have mushroomed, with crime syndicates luring, kidnapping or coercing workers into predatory online activity. 

The scam industry is raking in unprecedented sums, the equivalent of billions of dollars, according to the UN Office on Drugs and Crime. 

Victims have reported travelling across the region, often on the pretense of romance or high-paying jobs but finding themselves forced instead to cajole people into ploughing money into fake investment platforms and other ruses.

The Philippines police said a Malaysian worker had also sought help after allegedly being held against his will at the same address in Bamban.

At the center, a complex of 36 office buildings and dormitories, the victims were engaged in various online scams under threat of physical harm or other punishment, the authorities said.

"The (online gaming) workers who failed to achieve their quota... were physically harmed, deprived of sleep or locked up inside their rooms," Cruz said. 

Eight people are being held as suspects of illegal detention and human trafficking.

The Chinese embassy has been asked to help identify the suspects, Cruz said.

Reached for comment, a mission spokesman told AFP the request will be relayed to the Chinese authorities.

Cruz later told AFP an unspecified number of the Filipinos found at the site would be released without charges as they were "just there to work as maintenance or security" staff.

Last year, police detained nearly 3,300 people in two large-scale raids on what they said were scamming sites in Manila.