A Home Office impact assessment published on Monday said only 2,143 of the 5,700 asylum seekers Rwanda has agreed to accept from the UK attend regular check-ins and "can be located for detention".

This leaves 3,557 people not in regular contact.

However, government minister Victoria Atkins told Sky News: "Some are already detained in facilities, others are perhaps staying with friends or family. But the Home Office is in contact with much of the cohort.

"The Home Office is used to this, operationally, law enforcement officers are used to this.

"We want the message to go out loud and clear that if somebody doesn't report as they should do, they shouldn't think that they'll get away with it. They will be found.

"Law enforcement have a variety of measures to find people.

"They will be found and they will be removed.

"I don't pretend this is going to be easy. And we are very much doing this."

Ms Atkins insisted all 5,700 people identified in the first group "as well as others" will be sent to Rwanda by the end of the year.

Only asylum seekers who arrived between 1 July 2022 and 29 June 2023 and who already received a letter telling them about the Rwanda plan are in this first group.

The first flights are planned for this July, which indicates no one who arrived in Britain on a small boat during the previous year will be onboard.

Prime Minister Rishi Sunak said he wants the first flights to take off within 10 to 12 weeks after the law was passed last week.

The controversial law was passed after a bill was created stating that Rwanda should be regarded as a safe country "for the purposes of relocating people, including in UK courts and tribunals".

It suffered a number of setbacks and delays, including the Supreme Court ruling the scheme to send people arriving in the UK in small boats to Rwanda "unlawful" last year.

Ms Atkins added: "We want to deal with this. We don't pretend it's easy, but we believe that Rwanda is one of the many tools we have at our disposal."

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After the law was passed, Mr Sunak said there were now 2,200 detention spaces and 200 dedicated caseworkers had been trained to process claims quickly.

About 25 courtrooms have been made available and 150 judges will provide 5,000 sitting days, he added.

The prime minister also said there were 500 "highly trained individuals ready to escort illegal migrants all the way to Rwanda, with 300 more trained in the coming week".

Legal challenges are still expected, with campaigners saying they are identifying asylum seekers who may be singled out for deportation and will be lodging legal challenges.

A clash with the European Court of Human Rights (ECHR) - which blocked the first flight from taking off in June 2022 - could also be on the cards.