A new report into Bedfordshire's Yarl's Wood immigration detention centre says victims of modern slavery and sex trafficking are being "failed" by the Home Office.
The Women for Refugee Women report said some women were detained for months at the centre or released back to the addresses where they were abused.
It added, "These women have suffered extreme abuse and exploitation and do not receive the support and protection that is promised in policies.”
According to the report, nine women had been forced into prostitution in brothels or massage parlours, while five others were forced to work in restaurants including domestic servitude.
Many of the trafficking victims said their mental health deteriorated while at the Bedford-based facility.
All 14 women have since been released from the centre and are seeking asylum.
Yarl's Wood has come under repeated criticism in recent years, with an inspection in 2015 describing the centre as a "place of national concern".
"In all my time working with refugee and asylum-seeking women, I have never heard stories more harrowing than those we are hearing from Chinese trafficked women in detention. "They are locked up and threatened with deportation. This situation must change now."