Two migrants have died with a further 60 rescued after 100 squeezed into a makeshift boat as they attempted to cross the Channel into Britain.
The deaths, which took place overnight south of the beaches of Neufchatel-Hardelot in Calais, mean there have been at least 25 fatalities from Channel crossings this year.
About 60 people 'are currently being taken care of' following the incident, French officials said.
A record 32,000 migrants have arrived in Britain by crossing the Channel in small boats since January.
Under Labour's 'one in, one out' deal the UK can return migrants after arrival if they are deemed ineligible for asylum, including those who have passed through a 'safe country' to reach UK shores.
In return, London will accept an equal number of migrants from France who are likely to have their asylum claims granted.
The first migrants from France under Labour's deal arrived in the UK on Thursday.
A family of three, including a small child, came to Britain after successfully completing the online application process, the Home Office said.
Two migrants have died with a further 60 rescued after 100 squeezed into a makeshift boat as they attempted to cross the Channel into Britain
The deaths, which took place south of the beaches of Neufchatel-Hardelot in Calais, mean there have been at least 25 fatalities from Channel crossings this year
Four migrants have so far been sent back to France under the deal - one Indian national, one Eritrean, one Iranian and one Afghan.
Since the treaty came into force on August 6, 6,752 small boat migrants have crossed the Channel and reached Britain.
A Home Office spokesman said: 'The UK-France deal is a historic agreement, and these are critical first steps.
'This is a clear message to people-smuggling gangs that illegal entry into the UK will not be tolerated.
'We will continue to detain and remove those who arrive by small boat.
'And we will work with France to operate a legal route for an equal number of eligible migrants to come to the UK subject to security checks.'
Meanwhile, multitudes of destitute and desperate men originating from across the world are in the French city of Calais.
Scores of white charity vans with British and French number plates criss-cross the city from dawn to dusk delivering rice meals and water to the foreigners who live rough in woodlands near suburban streets, in charity tents perched on the quay in front of the Gothic town hall, or in the myriad squalid shanty camps dotted about the city.
Since the 'one in, one out' deal came into force on August 6, 6,752 small boat migrants have crossed the Channel and reached Britain.
The Red Cross is running emergency pop-up medical clinics to treat diseases including diphtheria and tuberculosis.
The Catholic Church has opened shower blocks in special shelters, and there is no shortage of customers.
Plastered on street signs in countless languages are notices from charities giving 'arrival' advice on how migrants can find 'English toilets', get a human rights lawyer, avoid police trouble, or access charity support to survive the winter ahead.
Huge white water butts are delivered by volunteers for migrants to wash their laundry in public.
So far this year 32,188 migrants have reached Britain by small boat, up 28 per cent on the same point last year.
But this year's tally has for the first time dipped slightly below the record levels seen in 2022, which went on to see an all-time high annual figure of more than 45,000.