A migrant died Wednesday trying to cross the Channel to Britain, French authorities said, while the date of death was not immediately clear for three more people found dead on beaches.
The finds bring the number of deaths this year linked to crossings in overcrowded dinghies to around 60.
With British and French authorities seeking to crack down on people smuggling gangs, activists say traffickers are now herding larger groups of migrants hoping for a better life in the United Kingdom into increasingly unsafe boats.
The man who died Wednesday was one of around 15 who fell into the sea off Hardelot in northern France, the French Maritime Prefecture of the Channel and North Sea said.
A helicopter transported the migrant to land where he was declared dead.
Fire chief Baptiste Gournay said the man was 28 years old, while prosecutors in Boulogne-sur-Mer said he "may have been Kuwaiti".
In total, 61 people were rescued, including one whose condition was very critical and another five also taken to hospital.
Gournay said three other migrants were also battling for their lives after a second rescue operation off the area of Merlimont, some 20 kilometres (12 miles) to the south.
Many people had tried to cross overnight and in the early morning as weather conditions were calm, the prefecture said.
Hours after the death, three migrants' bodies were discovered on separate beaches in northern France, including at Hardelot.
It was not immediately clear when the men might have died.
"For now, we're counting the dead," assistant prosecutor Patrick Leleu said.
On Wednesday morning, a deflated blue and black dinghy lay on the beach in Hardelot, an AFP journalist saw.
Rescue services, including fire trucks with their lights flashing, had been deployed on the shore.
Rescuers led around 20 migrants into a nearby building to warm up.
Some three kilometres (around two miles) away from the coast, journalists saw six soaked migrants, some wrapped in survival blankets, sitting on a bench.
A member of the Utopia 56 charity working with migrants said that several people were suffering from "severe hypothermia" after falling into the sea.
Increasing numbers of migrants and asylum seekers have crossed the Channel since 2018 despite repeated warnings about the perilous journey.
After the deadly accident on Wednesday, not far along the same beach, an AFP reporter saw some 70 people including children wade into the water to board a dinghy. Some had a life jacket, while others clutched a giant inflatable ring.
After the engine failed to start, around 40 people disembarked and returned to the beach.
The inflatable vessel eventually set off with around 30 on board.
Overnight, AFP journalists saw two groups depart in the dark from Sangatte, an area further north near the port city of Calais.
Utopia 56's Celestin Pichaud said the situation was "more than dramatic".
"For several months, it's been one person dying every five days" trying to cross the Channel, he said.
"Land and sea rescue services are completely overwhelmed."
Drownings and deadly crushes on overcrowded boats since January have made 2024 the most dangerous year for migrants trying to reach Britain by sea since 2018.
An Indian man died off the French coast on Sunday as he tried to cross the Channel.
On Wednesday last week, a woman and two men died after their small boat sank in the Channel off Calais.
The week before, a four-month-old baby died in an overloaded boat headed for the United Kingdom.
More than 1,500 migrants have landed on British shores over the past week, according to UK Home Office figures.
