Custodial functions may be discharged at a removal centre only by—
a detainee custody officer authorised, in accordance with section 154(1), to perform such functions; or
a prison officer, or a certified prisoner custody officer, exercising functions in relation to the removal centre—
in accordance with arrangements made under section 154(5); or
as a result of a contract entered into under section 150(1)(b).
Schedule 12 makes provision with respect to discipline and other matters at removal centres and short-term holding facilities and in pre-departure accommodation .