Six members of G4S staff have been sacked following undercover footage showing abuse of detainees at the Brook House immigration centre, it has been revealed.
The dismissals were confirmed as it was revealed that an independent inquiry commissioned by the company into events at the centre will be carried out by barrister Kate Lampard.
She conducted an earlier investigation into allegations of mistreatment at Yarl's Wood detention centre in Bedford.
In a letter to the House of Commons Home Affairs Committee, published on Tuesday, G4S president Peter Neden said the inquiry will look into "the extent and root causes of the treatment of detainees" at Brook House", near Gatwick Airport.
Immigration minister Brandon Lewis told the committee the Home Office would look closely at the outcome of the review "to make sure we do everything we can to make sure that abhorrent situation can't happen again either at Brook House (pictured) or anywhere else."
But committee chairwoman Yvette Cooper told him: "The issue for us is making sure there is a review of the Home Office practices and the Home Office responsibility for these detention centres and what the Home Office oversight is, because clearly it hasn't worked in this Brook House case.
"We will want assurances that it is going to work in other cases and isn't failing currently as we speak in other detention centres."
Brook House is one of two immigration centres run by G4S in the UK and has capacity for 508 adult men.
Undercover footage broadcast in September by the BBC's Panorama showed staff mocking detainees who were receiving medical treatment after self-harming or taking drugs, while one member of staff was filmed allegedly choking a detainee.
Mr Neden told the committee that Ms Lampard's inquiry will examine "G4S's management, operational and staffing arrangements and the practices and behaviours of G4S's staff" in relation to issues including the care and welfare of detainees, mental health, self-harm, violence prevention, the use of force, reporting of incidents and the availability of drugs
It will also cover "the attitudes and behaviour of staff towards detainees and the reasons why staff did not use the whistle-blowing procedures to report their colleagues' behaviour".
Ms Lampard's 2016 report on Yarl's Wood found "serious incidents of inappropriate behaviour" at the Serco-operated centre, near Bedford, and raised concerns about inadequate staffing levels, but said there was no evidence of a "widespread or endemic" culture of abuse.
In a hearing on Tuesday, Mr Lewis told the Home Affairs Committee, which is carrying out its own inquiry into events at Brook House, that the behaviour exposed by Panorama was "inappropriate (and) abhorrent".
He acknowledged that the activities had not been picked up by earlier inspections or by a Home Office official who was permanently based at the centre, but suggested the misconduct occurred only for a limited period of time.
"It looks like there was a period of time when individuals there were able to behave in a way that was completely unacceptable," said Mr Lewis. "It looks like that wasn't happening when the previous inspections were going on."
But Ms Cooper said: "The evidence we have heard is that this had been going on for quite some time and there were failures in the system for quite some time. This wasn't a recent problem."
Following the hearing, Ms Cooper said: "The Government has no explanation about why it did not know about the bullying and abuse at Brook House, despite the fact that a Home Office official was there every single day.
"Nor could they explain what was happening in other centres.
"I do not believe this is isolated to Brook House - the Home Office must ensure vulnerable people in their care, who may have experienced huge trauma in their lives, are treated with decency and respect."
Copyright (c) Press Association Ltd. 2017, All Rights Reserved. Picture (c) Gareth Fuller / PA Wire.