Conditions have become "unacceptable" for a small number of women at an immigration removal centre, the Chief Inspector of Prisons has said.
In a report on Tinsley House at Gatwick Airport, West Sussex, Anne Owers found some single women at the facility were "marginalised and almost forgotten".
Ms Owers also raised concerns about children, saying their detention for "days or even weeks was damaging".
The UK Border Agency (UKBA) is drawing up an action plan based on the report.
Inspectors said Tinsley House provided a "largely safe and respectful environment" for the male majority of the population.
But they found there were "no care plans" for children detained beyond seven days, and some staff lacked child protection training.
Inspectors also said there were "very few single women", and that these women were forced to share facilities in a mainly male establishment which could be "embarrassing and intimidating".
The report pointed to the issue as one which "urgently needed to be addressed".
Ms Owers said another removal centre, Brook House, was opening near the airport, and Tinsley House should become "a dedicated facility for families and single women".
The report released on Wednesday follows a full announced inspection of the centre in February.
A UKBA statement welcomed the part of the inspectors' judgement which found that Tinsley House remained a "safe and respectful" centre.
The UKBA said: "The safety and security of female and male detainees at Tinsley House is taken very seriously.
"Females have separate living accommodation and access to facilities such as the laundry or refectory at 'female-only' times."
It added that the centre was "noted for its considerable improvement in arrangements for children", including physical conditions, facilities and support from qualified care workers.