Home Secretary Yvette Cooper has declined to put a figure on how many migrants will be returned to France under a new scheme that comes into force today.
Some migrants arriving in the UK on small boats will be detained and returned to France under the deal agreed with French President Emmanuel Macron.
In return, the UK will accept asylum seekers who have not tried to cross and can pass security and eligibility checks.
Prime Minister Sir Keir Starmer said the plan was a “product of months of grown-up diplomacy” which would “deliver real results” but the Conservatives said it would “make no difference whatsoever”.
As of 30 July, more than 25,000 people had crossed the Channel in small boats in 2025 – about 49% higher than at the same point in 2024.
UK and international law prevents the government from sending asylum seekers back to their country of origin before their claim has been considered and turned down. However, they can be sent to safe countries prepared to consider their claim.
Under the plan, an adult migrant who tries to get to the UK by crossing the Channel could be returned to France if their claim for asylum was deemed to be inadmissible. Returns could begin to take place within weeks.
The BBC understands that anyone arriving in the UK via small boat will be assessed as being inadmissible, but mental health and security checks will still be made, followed by screening about suitability for detention and removal.
However, Cooper would not be drawn on how many returns were likely to be made, stressing the scheme starting up was a trial.
“The numbers will start lower and then build,” she told BBC Breakfast, saying the were two reasons for not setting out numbers at this point.
“First of all because those numbers will vary and will increase and we haven’t picked an overall number for the scheme, although we obviously want it to increase as much as possible.
“But also, second, because we’re not going to provide operational information about which numbers, which days, that the criminal gangs will then use to continue to ply their vile trade in human beings.”
There have been reports that 50 people per week could be returned, compared with the weekly average of more than 800 people currently making the crossing.
Peter Walsh, a senior researcher at the University of Oxford’s Migration Observatory, said the number of returns would need to be higher to have a deterrent effect.
Asked whether 50 returns a week would have an impact on crossings, he said: “On the current rate of arrivals, that would be roughly a 5% chance of being returned.
“People are already taking such a big risk, they’re risking their lives by getting in a small boat, so you’d have to imagine that that kind of percentage might not be enough to move the needle.
“Small boat arrivals are a very clear sign of a lack of control over the border. These are unauthorised arrivals and that’s why people are concerned.”
The government is under pressure to reduce the numbers, having promised to “smash the gangs” organising the journeys.
Sir Keir has previously said the “one-in-one-out” returns pilot scheme with France is not “a silver bullet” but he believes it will deter people from making the dangerous journey following a big increase in the numbers so far this year.
He announced the agreement with Emmanuel Macron in July, but it was still subject to legal scrutiny by the European Commission and EU member states.
At that point, the charity Asylum Matters criticised the measure, arguing: “The only way to stop people from making dangerous journeys is to give them real safe routes to seek sanctuary.”
The UK government has now said that the “EU Commission, Germany and other member states have given the green light on this innovative approach” meaning the scheme can go ahead.
On Monday, the government announced £100m to fund 300 National Crime Agency Officers to stop the people smugglers arranging the crossings.
It has also said it wants to tackle illegal working, reducing pull factors which encourage people to come to the UK.
Conservative shadow home secretary Chris Philp said the government’s deal with the French would be less effective than the Rwanda plan proposed by the previous Conservative government.
“The Rwanda removals deterrent, under which 100% of illegal arrivals would be removed, was ready to go last summer but Labour cancelled it just days before it was due to start with no proper replacement plan,” he said.
“As a result, this year so far has been the worst ever for illegal immigrants crossing the Channel.”
