Manila: Five foreigners were arrested for operating nightclubs in a former US Air Base in central Philippines, where hundreds of under-age sex workers were illegally trafficked from the south of the country.

Three Americans, a Japanese and an Australian were arrested after the Philippine National Police's Criminal Investigation and Detection Group (CIDG) launched several raids on Sunshine Bar, the Blue Nile and the Golden Nile night clubs on Fields Avenue in Balibago village on Tuesday, said CIDG director, Chief Superintendent Samuel Pagdilao Jr. in a statement on Wednesday.

The only detainee whose name was given out was Australian Terrence James Smith, manager of Sunshine Bar. Three of the other four remain in detention while one American has been released, said a source.

If convicted, they would be charged with human trafficking, which is penalised by life imprisonment.

About 17 women were rescued from the Sunshine Bar. The rest were from the other bars that were raided.

"Most of the women came from Mindanao. They were promised jobs as factory workers, waitresses or sales ladies," CIDG Women and Children's Protection Desk head Superintendent Emma Libunao told the Inquirer.

"They would wait tables at first, then they would start entertaining guests at the table. Some said they were 18. Or they were taught to say they're 18," she said, adding that women with labels saying: "I'm a virgin so I'm very expensive," were also offered to undercover agents before the raid.

The sex workers did not voluntarily join their rescuers, Libunao admitted.