The inflatable craft got into trouble early in the morning due to the unseasonal “poor weather and worsening sea conditions”.
After French prosecutors opened a criminal inquiry, Philippe Sabatier, the prosecutor for the coastal city of Bologne, said: “Six Afghan males died, and the vast majority of those involved were also from Afghanistan. They included minors.”
At least two people were still missing tonight as search efforts on both sides of the Channel continued.
An emergency was declared when the boat – with around 66 people on board – was spotted struggling off Sangatte, a beach west of Calais.
French Navy patrol boat Cormoran was the first vessel to spring into action on the northern coast and begin rescuing dozens of survivors.
Five Afghan men in their 20s and 30s were declared dead at the scene, while a sixth was airlifted to the French seaside town of Le Touquet.
He later died in hospital in Calais.
Another small migrant boat sank elsewhere in the Channel today.
It is reported that 22 people were saved in that incident, including one “in a critical condition”.
None of the victims’ identities were known last night, as many of them were travelling without papers.
A total of 49 survivors were rescued from the first boat – 36 by the French, and 13 by the British.
Natalie Elphicke, Conservative MP for Dover, Kent, said: “This tragedy underlines why we must stop the small boats to keep people safe and prevent loss of life in the Channel.
“These overcrowded and unseaworthy deathtraps should obviously be stopped by the French authorities from leaving the French coast in the first place.
“The time has come for joint patrols on the French coast and a cross-Channel security zone before any more lives are lost.”
The other French vessels involved in the rescue operations were the Pluvier, the Abeille-Normandie and the lifeboat of the National Sea Rescue Society of Calais, Notre-Dame de Risban.
Crews from two British ships also raced out in support – the RNLI 1709 lifeboat from Dover’s port and a private vessel.
Home Secretary Suella Braverman released a statement calling the deaths of the six men “tragic”.
She said: “My thoughts and prayers are with those affected by the tragic loss of life in the Channel.
“I have spoken with our Border Force teams, who have been supporting the French authorities in response to the incident.”
Shadow Home Secretary Yvette Cooper warned that it is “desperately” necessary to stop the dangerous 20-mile crossings and “the terrible criminal smuggling gangs who profit while lives are lost”.
Steve Smith, chief executive of refugee charity Care4Calais, described it as an “appalling and preventable tragedy”.
In a previous Channel disaster on November 24, 2021, an inflatable dinghy with 29 people on board collapsed mid-journey.
The 27 who died were later identified as 16 Kurds from Iraqi Kurdistan, four Afghans and five other nationalities.
French emergency workers in a telephone centre were later blamed for failing to answer their distress calls properly.
The people smugglers responsible for supplying the vessel and setting up the journey have never been brought to justice.