Chief inspector of prisons Charlie Taylor was so concerned by what he found during the visit in February that he wrote to then home secretary James Cleverly but received no reply.
The visit to Harmondsworth Immigration Removal Centre revealed “chaos” that was “truly shocking”, including violence and drug taking.
There had also been numerous suicide attempts made by people being held there, including an attempt during the inspection of the centre that led to “serious injuries to the detainee”.
Inspectors found the support for those who had said they felt suicidal was “not good enough”.
A Home Office spokesperson said: “We take the welfare and safety of people in our care very seriously and it is vital that detention and removals are carried out with dignity and respect.
“The number of custody officers and dedicated welfare staff at Harmondsworth IRC has been increased since the inspection.”
