At least three children and a pregnant woman were feared to be among 27 migrants who drowned in the Channel when a flimsy, overcrowded dinghy sunk.
As the full horror of the tragedy was emerging, a fifth suspected member of the people smuggling gang that arranged the crossing was arrested.
French prosecutors are carrying out a criminal probe into the deaths, as Britain today offered more support to boost patrols on French beaches to stop boats being launched.
It came as:
Local reports, which have not been confirmed, suggested the inflatable craft was hit by a container ship and that it deflated like a paddling pool.
The victims were said to include a teenage boy and a young girl, with a number of them believed to be Iraqi Kurds or from Somalia.
Bernard Barron, president of the SNSM rescue service in Calais, spoke of “group murder” as another rescuer described how the “floating death trap” that was meant to contain a maximum of 10 people “was completely deflated when we found it”.
Dozens of migrants, believed to be in two boats, still risked their lives on Thursday to make the crossing to Britain in freezing, windy conditions. A group wearing life jackets and wrapped in blankets were seen huddled together on an RNLI lifeboat before disembarking in Dover.
French police from Calais helped to rescue 20 migrants whose boat filled with water as they left a beach on Wednesday night.
French interior minister Gérald Darmanin accused the UK of bad management of its illegal immigration problem. Immigration minister Kevin Foster hit back, saying “fingerpointing is not very helpful” and that Britain was offering more resources, including for patrol beaches, to tackle the crisis.
Home Secretary Priti Patel was due to speak to Mr Darmanin on Thursday morning before updating MPs this afternoon.
Boris Johnson accused France of failing to do enough to stop migrants from crossing the Channel, saying gangsters smuggling people were “literally getting away with murder”.
French president Emmanuel Macron told the Prime Minister in talks on Wednesday night that the Government should not seek to use the tragedy for political purposes, the Elysée Palace said
Just two men, an Iraqi Kurd and a Somalian, made a “miracle escape” from the sinking dinghy. They have indicated that a container ship collided with them, according to rescuers.
Migrants who had boarded it in the hope of reaching Britain had paid the equivalent of up to £6,000. Very few of them were wearing life jackets, and most are thought to have succumbed to hypothermia in the water.
Seven were women, including one expecting a baby, while three children were also among the deceased, according to local reports. Autopsies will take place in Lille in the next few days, said Carole Etienne, the city’s public prosecutor, who is leading a criminal inquiry.
Mr Barron said: “Migrants are forced into the boat, and their feet are in water and fuel. These are unimaginable conditions. Often only women and children have life jackets, and the boats don’t have navigation lights or radar receivers.”
Charles Devos, also one of the first SNSM rescuers to reach the victims, said: “The inflatables are only designed for 10 people, but more than 50 have been packed on board, turning them into floating death traps.
“We always thought that, one day or another, they were going to collide with a container ship or a ferry.”
The rescuers believe the boat left Loon-Plage, near Dunkirk, on Wedneesday morning and collided with a ship at the limit of French territorial waters. A fisherman sounded the alarm at about 2pm after he saw corpses in the sea.
Four men were held near the Belgium border. A fifth man was arrested later. All face charges of manslaughter and “assistance with illegal immigration in an organised gang”.
Mr Darmanin said 255 migrants reached the UK on Wednesday. These included about 40 allowed into the sea near Boulogne as at least two police officers appeared to do nothing.