The Tongan Women's Crisis Centre says it has been contacted by foreign girls and women who've been caught up in trafficking and forced prostitution in the kingdom.
Ofa ki-levuka Guttenbeil Likiliki says these women claim that brothel-type operations exist behind the facade of some restaurants.
She says they are scared because their passports have been taken off them.
But she says the centre is working to provide assistance and help.
"The language barrier is there, but we do know, we've been contacted by a few of these girls and you know they're seeking our help."
Ofa ki-levuka Guttenbeil Likiliki says the Centre has been following Tonga's first case of human trafficking in the Supreme Court closely.
A Chinese woman, Liu Lirong, was found guilty on seven charges - four for trafficking persons into Tonga, one for keeping a brothel and two counts for trading in prostitution.
She will be sentenced next month.