The British authorities have begun a series of operations to detain migrants in preparation for their deportation to Rwanda as part of Prime Minister Rishi Sunak’s flagship immigration policy.

The UK Home Office, which oversees immigration matters in the United Kingdom, released a video on Wednesday showing armed immigration officers handcuffing individuals at their homes and escorting them into deportation vans.

In a statement, it announced a “series of nationwide operations” ahead of the first deportations to begin in the next nine to 11 weeks. Interior minister James Cleverly said enforcement teams were “working at pace to swiftly detain those who have no right to be here so we can get flights off the ground”.

BREAKING: The first people set to be removed to Rwanda have been detained. pic.twitter.com/2WWNhQVC1l

— Home Office (@ukhomeoffice) May 1, 2024

Last month, Parliament approved a controversial law – known as the Safety of Rwanda Bill – that allows for asylum seekers who arrive illegally in Britain to be deported to Rwanda, even after the UK Supreme Court declared the policy unlawful last year.

Sunak, who is expected to call an election later this year, said the flagship immigration policy seeks to deter people from crossing the English Channel in small boats and to tackle the issue of people-smuggling gangs.

Unions and human rights charities have expressed dismay at the wave of arrests so far. While some have succeeded in blocking transfers to removal centres, they say it is becoming increasingly difficult to bring legal action.

Who is being targeted by the campaign of mass arrests?

The Home Office has announced it is carrying out arrests within an initial cohort of about 5,700 men and women who arrived in the UK without prior permission between January 2022 and June 2023. Those who fall within this group have been sent a “notice of intent” stating that they are being considered for deportation to Rwanda.

However, it was revealed this week that government data shows that the Home Office has lost contact with thousands of potential deportees, with only 2,143 “located for detention” so far. More than 3,500 are unaccounted for, with some thought to have fled across the Northern Irish border into Ireland. Others include people who have failed to attend mandatory appointments with the UK authorities. Ministers have insisted enforcement teams will find them.

Several asylum seekers who did attend compulsory appointments with the UK authorities as part of their application for asylum this week have been arrested and told they will be sent to Rwanda.

Fizza Qureshi, CEO of the charity Migrants’ Rights Network, told Al Jazeera that “people are forced to go and report in these Home Office centres and once they are there, there is no guarantee that they’ll come out free”.

The government has not provided exact figures for the number of arrests conducted since the operation started on Monday, but detentions have been reported across the UK in England, Wales, Scotland and Northern Ireland and in cities including Bristol, Liverpool, Birmingham and Glasgow.

Maddie Harris, founder of the UK-based Humans for Rights Network, told Al Jazeera that asylum seekers from war-torn countries including Afghanistan, Sudan, Syria and Eritrea with no connection to Rwanda are being arrested as part of the scheme.

One of the organisation’s clients, a young woman who has been in the UK for almost two years, was arrested as part of the crackdown. “She is absolutely terrified,” Harris said, adding that while the young woman has no connection to Rwanda, she was told she would be deported to the Eastern African country.

According to Humans for Rights Network, individuals who have filled out a Home Office questionnaire over the past two years were also being arrested. The organisation said it had initially believed completing the form indicated that the client had been admitted into the UK asylum system and could not be deported.

That assumption has been proven false and “that’s very concerning”, Harris said.

How is the arrest campaign affecting the people being targeted?

Rights groups, including Migrants’ Rights Network, have been successful in blocking the transfer of some people to removal centres in several cases, but Qureshi said it required “24/7 resistance” for each individual case.

Qureshi added that the arrests have had a chilling effect, pushing asylum seekers to evade authorities and into exploitative situations. “Raids push people underground and away from support systems,” she said. “There is no safe option for people and that has been made clear.”

Natasha Tsangarides, associate director of advocacy at Freedom from Torture, said detentions run the risk of rekindling pre-existing trauma in people who were subject to torture or ill-treatment, while also driving them away from support systems.

“Clinicians who work with torture survivors every day in our therapy rooms have recognised that many will experience re-traumatisation even with a very short time in detention,” Tsangarides said, adding that this would deteriorate trauma symptoms.

“Not only does this legislation place people at risk of harm if they are sent to Rwanda, but it spreads such terror in the community that we worry people may go underground to avoid taking any risk.”

The UK government has not ruled out sending survivors of torture to Rwanda.

Could legal action stop the deportations?

The ruling Conservative party’s plan to deport immigrants who have entered the UK without permission to Rwanda has faced more than two years of legal hurdles and political wrangling between the two houses of Parliament.

In June 2022, the first flight taking refugees to Rwanda was stopped at the last minute by the European Court of Human Rights (ECHR). Last year, the UK Supreme Court declared the deportation scheme unlawful on the basis that the government could not guarantee the safety of migrants once they had arrived in Rwanda.

The Safety of Rwanda Bill, which was passed on April 23, circumvented the Supreme Court ruling by designating the East African country as a safe destination, paving the way for deportations to begin.

The Illegal Migration Act, which became law in July 2023, also stated that anyone who arrives in the UK on small boats will be prevented from claiming asylum, detained and then deported either back to their homelands or to a third country, such as Rwanda.

Jonathan Featonby, chief policy analyst at Refugee Council, told Al Jazeera that both legislations severely limit the ability of people to challenge their removal to Rwanda through the courts.

Under the plan, asylum seekers arriving illegally in the UK can be sent to Rwanda to be processed within the East African country’s legal system and will not be able to return to the UK.

“In reality, people’s ability to continue that challenge and get the support they need to go through that process is severely limited,” Featonby said. “There are some legal organisations coming together to make sure they can provide legal support and challenge both individual cases and the legislation itself, but it is quite unclear how successful those challenges will be.”

The senior civil servants’ union FDA on Wednesday submitted an application for a judicial review against the government’s Rwanda plan, arguing that it leaves its members at risk of breaching international law if they follow a minister’s demands.

Featonby said appeals can also be filed at the European Court of Human Rights, “but that will take time and it will likely not prevent someone from being removed to Rwanda in the meantime”.

“Not only is the legislation dehumanising people coming to the UK to seek protection, but it is shutting down the asylum process,” he added.

“We are calling for the whole plan and the Illegal Migration Act to be scrapped and for the government to run a fair, efficient and humane asylum system.”