The Fiji-based NGO, Women's Crisis Centre, says many women forced into the sex trade are in the region illegally.
Officials say more and more women, mostly of Chinese origin, are being moved into the Pacific and then forced into prostitution.
In a new suspected case in American Samoa, a Chinese couple faces multiple charges, including promoting prostitution and kidnapping five Chinese women.
The five Chinese sex workers are in custody because they were found to have questionable documents as their visas were duplicated and had also expired.
The Women's Crisis Centre's Shamima Ali says this happens too often.
"Our immigration department has been under the spotlight for the past two or three years about how people got in here. A lot of it has to do with our own corrupt officials who allow people in."
However, the Pacific Immigration Directors Conference's Matthew Gibbs, says they mostly have the papers, but it is the additional coercion into prostitution that makes things illegal.