Scandal-hit security privateer Serco has fired two immigration centre guards following a government inspection for having sex with a vulnerable detainee.

A third employee at the company’s Yarl’s Wood women’s centre in Bedfordshire was also sacked for failing to take any action when the female detainee reported the two men.

HM Chief Inspector of Prisons Nick Hardwick said: “We were concerned to find that two staff had engaged in sexual activity with a female detainee, something that can never be less than abusive given the vulnerability of the detained population, and these staff had rightly been dismissed.”

Yarl’s Wood holds mainly single adult women but also holds a number of adult families and there is a short-term holding facility for adult men.

Inspectors concluded that more female staff were needed urgently as there were not enough for a mainly women’s establishment.

A number of women at the centre — where none of the detainees have been charged with an offence or held through normal judicial procedures — were detained for long periods, including one for almost four years.

The inspection found pregnant women had been held without evidence of exceptional circumstances required to justify their captivity.

One of the women had been admitted to hospital twice because of pregnancy-related complications.

And detainees who may have been victims of human trafficking — such as one woman who had been picked up in a brothel — had not been referred to the national trafficking referral mechanism, as required.

Refugee Council women’s advocacy and influencing officer Anna Musgrave said: “Women in immigration detention are extremely vulnerable, so we’re horrified to hear that male officers enter women’s rooms without permission.

“It’s particularly disturbing that officials are not even following current policy and pregnant women are being detained without any clear reason.

“There is absolutely no excuse for compromising the health and well-being of a mother and her baby.

“This report shows that urgent changes are needed at Yarl’s Wood to ensure that vulnerable women feel safe and that their dignity is respected.”

Police are currently investigating allegations of sexual misconduct at Yarl’s Wood, while Serco is under investigation for serious fraud.