The UK will pay for 200 French officers to detain and deport people seeking asylum from some of the world’s most oppressive and war-ravaged regimes under a new UK-France deal to try to reduce Channel crossings.

In what is being billed as the first time the French government has agreed to target those heading to the UK in small boats, a removal site in Dunkirk will be used to hold people from 10 countries: Eritrea, Afghanistan, Iran, Sudan, Somalia, Ethiopia, Iraq, Syria, Vietnam and Yemen. The Home Office said they were the top 10 nationalities who crossed the Channel by small boat last year.

They would be detained by officers paid for by the UK and deported to their home countries or other EU countries they had passed through, officials said.

Officials claim that hundreds, possibly thousands, will be detained under the scheme. However, EU countries, including France, have previously struggled to deport people to neighbouring countries under the Dublin agreement.

Jo Cobley, the chief executive of Safe Passage International, said it was “disgraceful and unlawful” to deport people to unsafe countries.

“With no accessible safe routes and the government’s suspension of refugee family reunion, the only way to reach the UK to ask for protection is across the Channel – punishing people with detention, deportation threats and police violence does not change that,” she said.

“It’s disgraceful, and unlawful, to return people to active war zones or where they face persecution, in countries like Afghanistan, Sudan and Iran, and to target people who would have very likely been granted protection in the UK.”

Home Office sources said French officials would prioritise people from those 10 countries because of UK concerns that they were fuelling the small boats crisis in the Channel. Sources said French access to the Eurodac database meant they could swiftly remove people who had passed through a third EU country.

Officials said the site in Dunkirk, which has a 140-person capacity, was expected to be in operation by the end of 2026.

First pledged by Rishi Sunak’s government in 2023, the site is still under construction with none of the buildings yet completed.

The approach of targeting people by their nationalities would be trialled using existing capacity at a nearby removal centre in Coquelles from next month.

Investment in the new detention centre forms part of the £160 million flexible, results-based pot. If it was not delivering value for money and proven results in its first year, the funding would be withdrawn from the scheme.

Sile Reynolds, the head of asylum advocacy at Freedom from Torture, said: “Caring people across the country will be outraged to discover their money is funding the detention of survivors of torture and war in France.

“People like the survivors we support who have fled unimaginable atrocities from conflicts in Sudan, Iran and Eritrea. People whose only ‘crime’ was hoping the UK would offer them sanctuary.”

She said survivors of torture and trauma should never be detained. “Even the briefest period in detention can cause profound damage, increasing the risk of suicide and self-harm. The idea that they will be swiftly returned to their home country is grossly misleading, bearing in mind the risk of persecution that so many of these people face on return.”

The deal was signed on Thursday by Shabana Mahmood, the home secretary, and her French counterpart, Laurent Nunez, at a ceremony in Dunkirk on Thursday. The French government normally take 30 days from detaining migrants to deportation.

The detain-and-deport approach is part of the £162m extra “payment-by-results” funding on top of the £500m deal agreed for the next three years to March 2029.

A 50-strong riot squad would be trained in “crowd control tactics” and would “stop illegal migrants in their tracks”, according to the Home Office. UK funds are expected to pay for batons, shields and teargas to deal with “hostile crowds and violent tactics”.

The announcement follows protracted negotiations between the two countries over how to halt unauthorised small boat journeys, and who should pick up most of the cost. The previous £478m, three-year deal collapsed on 31 March.