MANILA, Philippines (AP) — China should do more to battle the illegal online gambling and scam call centers run by Chinese criminal syndicates in Southeast Asian countries often using forced labor, a Philippine senator who led an investigation into the centers said Friday.

The U.N. human rights office has said that such gangs have forced hundreds of thousands of people into participating in online scam operations, including false romantic ploys, bogus investment pitches and illegal gambling schemes.

Sen. Risa Hontiveros also called for stronger international cooperation to end cybercrime, saying that the gangs undermine the rule of law and could provide a platform for espionage activities, although she acknowledged there is no clear evidence linking the gambling hubs to Chinese surveillance operations.

A number of Chinese gambling complexes which have been shut down by Philippine authorities were located near a Philippine air force base north of Manila where American forces have been authorized to build a presence and near a residential compound inhabited by American diplomats and military officials, according to Hontiveros.

China has expressed alarm over increased U.S. military deployments in Asia, including in the Philippines, Washington's longtime treaty ally.

Chinese-run online gambling outfits are estimated to number more than 400 across the Philippines, and they employ tens of thousands of Chinese and Southeast Asian nationals, many of them illegally trafficked into the country, Philippine officials said.

President Ferdinand Marcos Jr. ordered a ban on online gambling operations in July, saying they have mocked Philippine laws and committed crimes including financial scams, human trafficking, torture, kidnappings and murder.

China has banned gambling, but most of the clients of the online syndicates which operate in the Philippines were mainland Chinese citizens, who defy their government’s prohibition, Hontiveros said.

"China is not doing enough, given her impressive powers that she has not been shy to wield and display on so many fronts,” Hontiveros said.

"We would all benefit from more regional and international cooperation in, for example, making the social media companies more accountable for the use and misuse of their products and services, their platforms, for these malign operations,” Hontiveros told foreign news correspondents in a briefing.

There was no immediate reaction from Chinese officials in Manila or Beijing.

The Chinese government, however, has said it has cooperated with Filipino authorities in shutting down the online gambling and scam outfits of Chinese syndicates in the Philippines and rescuing large numbers of Chinese and other Southeast Asians who were illegally recruited and forced to run the illegal operations and scams.

Lucrative online gambling operations catering to Chinese citizens have also flourished in Southeast Asian countries allied with Beijing, including Cambodia and Myanmar, Hontiveros said.

The online gambling industry has flourished across the Philippines largely due to corruption in government regulatory agencies and big payoffs to officials, officials said.

The mayor of a town in Tarlac province north of Manila was dismissed by authorities after she was linked to an illegal online gambling complex with dozens of buildings.

The former mayor, Alice Guo, has also been accused of faking Filipino nationality to run for public office in 2022.

Guo fled the Philippines after the Senate committee led by Hontiveros ordered her arrest for failing to attend public hearings, but was arrested in Indonesia two weeks ago and deported to Manila.

Guo, who remains in detention, has denied any wrongdoing.