Thirty 'pop-up brothels' appear in Swindon each week
Up to 30 "pop-up brothels" appear in Swindon each week, police have said.
Wiltshire Police said in any one week up to 40 foreign sex workers were advertising their services in the town, the majority of whom were "transient".
The women use rented properties for between one day and a few weeks before packing up and moving on.
Many of the pop-up brothels are linked to organised crime gangs, with women being trafficked from Poland and Romania.
Det Sgt Chris Hitchcock said: "Many of these women move between addresses within the town as well as outside of it.
"Of these 40, we estimate they populate 20 to 30 brothels in short-term to medium-term rental properties."
He added that officers "look to intervene and see if we can offer safeguarding, and see if organised crime is involved, as often as we can".
He said the force was currently monitoring a total of between 170 and 190 women involved in sex work "predominantly" in Swindon.
A study last year by the Police Foundation found women in pop-up brothels were more likely to be trafficked than in standard brothels.
The number of reports of suspected brothels in Swindon nearly doubled between 2014 and 2015.
The issue of pop-up brothels moving into residential streets will be investigated as part of BBC Inside Out West at 19:30 GMT on Monday 6 February, and available afterwards on BBC iPlayer.