Manston is a non-residential centre with limited facilities, where people are meant to be kept only for short periods before being moved into more permanent accommodation, usually a hotel.
Opened as a processing centre in February, it has struggled to cope with the current 24-hour timeframe that applies to such sites.
Now a legal tweak will allow detention for up to 96 hours – a period that can be extended further by the home secretary in “exceptional circumstances”.
Pressure on the site has increased as the year has gone on, with the number of people crossing the Channel in small boats rising to record levels.