Accredited official statistics

How many people are detained under immigration powers in the UK?

Published 27 February 2025

Back to ‘Immigration system statistics, year ending December 2024’ content page.

Data on detentions relates to 2024 and all comparisons are with 2023 (unless indicated otherwise).

An individual may be detained under immigration powers under certain circumstances. This includes detention in support of the return of the individual with no legal right to be in the UK. In some cases, individuals may be detained whilst their identity is being established or where there is a risk of absconding.

1. People entering immigration detention

20,604 people entered immigration detention in 2024 under immigration powers.

The number of cases of people entering detention in 2024 increased 12% compared with the previous year. This uptick follows a long-term downward trend since 2015.

Figure 1: People entering immigration detention in the UK, 2015 to 2024

Source: Immigration detention - Det_D01

Figure 1 shows the number of people entering detention reduced from a peak of around 32,700 people in 2015 to around 24,500 in 2019. The reduced use of immigration detention over this period can in part be linked to the Government’s response to the 2016 Stephen Shaw review of detention, which proposed a range of changes in the use of detention and greater use of alternatives.

While 2020 and 2021 was impacted by the COVID-19 pandemic, the general downward trend in the number of people entering detention continued up to the year ending September 2023. This reduction in part reflects the move to process small boat arrivals outside of the detention estate, on arrival at the Manston facility. This has allowed more individuals to move directly to community-based accommodation, following the initial examination and checks, rather than be held in immigration detention, as was often the case up until early 2022.

Albanians were the most common nationality entering detention (6,031), accounting for just under one-third of the total in 2024.

Albanian nationals have been the most common nationality entering detention since the peak in Albanian small boat arrivals in late summer 2022. However, since 2022, annual numbers of Albanians entering detention have been falling, and in 2024 was 22% lower than the 7,698 detained in 2022. This follows a sharp downward trend in Albanian small boat arrivals over the same period.

There has been a rise in numbers of Romanian and Brazilian nationals, the second and third most common nationalities entering detention in 2024, whose numbers increased by around a third (32% and 34% respectively) during the year.

2. People in immigration detention

On 31 December 2024, 1,940 people were being held under immigration powers in the UK.

The number of people held in detention (that is, either in an immigration detention facility or in prisons under immigration powers) was 9% higher at the end of 2024 than one year earlier.

Figure 2 shows that the number of people in detention decreased sharply at the start of the COVID-19 pandemic, but has since returned to levels similar to those seen just prior to the pandemic.

The vast majority of people detained under Immigration powers are detained in the immigration detention estate rather than prisons. On 31 December 2024 there were however 107 foreign national offenders (FNOs) detained in prisons under immigration powers and this number has been around 100 since the second half of 2023. Around this time, some FNOs who had served their custodial sentence in prison started being transferred into the immigration detention estate if assessed suitable and low risk, to address prison capacity constraints. Prior to this change, the number of people detained in the prison estate were typically higher, ranging between 300 and 700 in the period from late 2017 to early 2023

The total number of foreign nationals held in prison for criminal offences can be found in the latest prison population statistics, published by the Ministry of Justice and HM Prison and Probation Service.

Figure 2: People detained under immigration powers in the UK, on the last day of the quarter, 31 December 2017 to 31 December 2024¹

Source: Immigration detention - Det_D02

Notes:

1. The ‘detention estate’ comprises Immigration Removal Centres (IRC), Short-Term Holding Facilities (STHF) and Pre-departure Accommodation (PDA). It is separate to those who are detained under immigration powers in prisons – these are shown separately on the chart.

The number of people in detention is a snapshot relating to a single point in time but numbers fluctuate daily. If a large number of people entered detention just before the end of a reporting period, the number of people in detention reported in these statistics would be higher than if the same people entered a few days later.

3. People leaving immigration detention

Just over a third (37%) of people leaving detention in 2024 were detained for between 8 and 28 days. The proportion of those staying 7 days or less was 28% in 2024.

Figure 3 shows that the proportion leaving detention within 7 days or less (28%) is less than half the proportion in 2021 (76%). Shorter detention durations were more common in 2021 because of high numbers of small boat arrivals that year who were at that time still being detained initially for short periods on arrival within the detention estate.

In the years 2010 to 2017, prior to the rise in small boat arrivals, the proportion of detentions lasting 7 days or less was higher than in 2024 (28%), averaging 37% over the period. A lower proportion were detained for the 8- to 28-day range over this time (27% compared to 37% in 2024).

Figure 3: People leaving immigration detention, by length of detention^1,2, 2010 to 2024

Source: Immigration detention - Det_D03

Notes:

1. ’<’ means ‘less than’.
2. The legend follows the same order and orientation as the stacks within the bars.

The most common reason for leaving detention in 2024 was bail (51%).

Figure 4 shows that the number of detainees leaving detention on immigration bail in 2024 is similar to the number being returned to another country on leaving detention (representing 44% of leavers). While the proportion of bailed cases has been higher than the proportion of returned cases since 2015, the difference in size between these groups has narrowed sharply since the end of the pandemic. This trend has resulted from a near tripling in the number of returns from detention, combined with a 51% fall in detainees leaving on bail since 2021.

Figure 4: People leaving detention by reason for leaving^1,2,3,4, 2010 to 2024

Source: Immigration detention - Det_D03

Notes:

1. Bailed Secretary of State (SoS) and Immigration Judge (IJ).
2. Other reasons for leaving detention include being sectioned under the Mental Health Act, entering criminal detention, being granted leave to enter (LTE) or remain (LTR) in the UK, being detained in error and people whose reason for leaving was not available at the time of publication. See the user guide for more details.
3. The legend follows the same order and orientation as the stacks within the bars.

The proportion of people leaving detention to be returned has increased from 39% in 2023 to 44% in 2024, and is now at similar levels seen from 2015 to 2018.

Numbers of detainees being returned from the UK upon leaving detention has more than doubled since 2022 to 8,893 in 2024. Albanian nationals made up 29% of the total leavers being returned in 2024, and 36% in 2023. This followed an agreement between the UK and Albanian governments, the UK-Albania Joint Communique to deter and disrupt illegal migration and criminal networks, being signed towards the end of 2022.

The increase in numbers of returns from detention over the last few years follows a longer term fall that can in part be linked to increasing numbers of detainees raising issues that prevented their return, as described in the Home Office research paper ‘Issues raised by people facing return in immigration detention’ (2021). This research showed that 73% of people detained within the UK following immigration offences in 2019 were recorded as having raised one or more issues that may have delayed or prevented their return. These issues included raising an asylum claim, making a legal challenge, or a claim to be a potential victim of modern slavery or human trafficking.

Further information on the number of people returned can be found in ‘How many people are returned from the UK?’ chapter of the Immigration system statistics quarterly release.

4. About the statistics

The statistics in this section relate to detention solely under immigration powers.

One individual may enter or leave detention multiple times in a given period and will therefore have been counted multiple times in the statistics.

5. Data tables

Data referred to here can be found in the following tables:

• Immigration detention summary tables
• Detailed immigration detention datasets

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See section 6 of the ‘About this release’ section for more details.