The first small boat migrants have been detained for removal to France under the new ‘one in, one out’ scheme.

The Home Office confirmed Channel arrivals were held after they were brought into Dover yesterday.

It did not disclose how many migrants had been held.

Nevertheless, these detentions occur amid significant concerns that human rights issues and other legal hurdles could postpone the return of migrants for several months, with doubts also surrounding the limited reach of the program.

Migrants selected for removal will be held in Home Office detention facilities rather than being sent to live in taxpayer-funded asylum hotels.

Home Secretary Yvette Cooper stated: ‘Yesterday, aligned with the stipulations of this pioneering new treaty, the first set of individuals crossing the Channel were detained upon their arrival at Western Jet Foil [at Dover port] and will remain in detention until they can be sent back to France.

‘This action sends a clear message to any migrants contemplating paying criminal networks to reach the UK that embarking on a small boat means risking their lives and wasting their money.

‘No-one should be making this illegal and dangerous journey that undermines our border security and lines the pockets of the criminal gangs.’

Migrants were detained at Dover yesterday (pictured is a group arriving on a Border Force cutter) 

An overloaded dinghy of migrants in the Channel yesterday 

She further mentioned: ‘Criminal organizations have spent the past seven years establishing themselves along our border, and dismantling their operations will require time. However, these detentions represent a crucial step forward in disrupting their business operations and dismantling their false assurances.

‘These are the early days for this pilot scheme, and it will develop over time.

‘Nonetheless, we are making progress in achieving what no previous government has managed since this crisis began – returning small boat arrivals to France and enhancing our borders through the Plan for Change.’

As part of the treaty Britain will accept migrants from France in exchange for small boat arrivals.

That element of the scheme also began today, allowing migrants to lodge ‘expressions of interest’ on a specially-created Home Office website.

It comes after a Cabinet minister appeared to contradict the terms of the new treaty with France yesterday.

Culture Secretary Lisa Nandy noted that small boat migrants returned under this agreement would have their human rights claims assessed after being sent back to France.

However, it later emerged that some types of human rights cases would, in fact, block the Home Office from being able to remove migrants in the first place.

Home Secretary Yvette Cooper confirmed the first group of migrants had been detained 

The treaty clearly sets out how small boat migrants cannot be sent back to France if they have ‘an outstanding human rights claim’. 

The Home Office confirmed some human rights claims will block migrants’ removal until they have been concluded in full.

It will include cases which cannot be formally ‘certified’ by officials as ‘clearly unfounded’.

The Mail has learned pro-migrant groups have begun informal discussions about launching a joint legal action against Labour’s plan – just as they did against the Tories’ Rwanda asylum scheme.

Sources said there had already been ‘a certain amount of co-ordination’ between charities and other groups, with details of the treaty still being analysed.

Meanwhile, the Free Movement website, which offers advice to immigration lawyers, yesterday published an analysis of the new measures which said: ‘Legal challenges will be more difficult than for Rwanda, however there are still likely to be grounds on which some people can resist removal to France.

‘For example, if the inadmissibility decision was wrong, if people have family in the UK, or had experiences in France which make it inappropriate to send them back.’

It means the Home Secretary is likely to face a huge legal battle to get the first migrants removed from Britain. 

Last month Prime Minister Sir Keir Starmer pledged migrants would be ‘detained and returned to France in short order’ under the agreement.

But yesterday – the first day it was in force – Shadow Home Secretary Chris Philp posted videos from the Channel as he watched migrant boats bound for the UK coast, escorted by a French vessel.

He said it showed the Anglo-French deal was a failure, adding that occupants of the boats were ‘coming to a hotel near you soon’.