A man has died after being airlifted to hospital from the English Channel after a boat carrying around 40 people began to sink.
French media have reported the death of the person, who was taken to Calais by helicopter earlier on Thursday.
The boat is believed to have begun taking on water as it headed for the UK on Thursday morning.
The rescue operation, involving French and Belgian air and sea units, is ongoing, authorities in France say.
Others are thought to have succeeded in reaching British shores on Thursday, with reports of a beach landing in Kent.
Searches started at around 10am after a cargo ship reported that a boat carrying around 40 people was in difficulty, with some people overboard, off the coast of Dunkirk.
An unconscious person taken aboard the cargo ship’s lifeboat and transferred on to a French Navy vessel was later airlifted to hospital in Calais.
He was believed to have suffered cardio-respiratory arrest and was evacuated aboard a Belgian Air Force helicopter, French authorities say.
French media have since reported that the individual has died.
Several others were also hoisted aboard the helicopter as the boat was sinking, while more were rescued by nearby fishing boats.
They were all transferred on to the French Navy’s Flamant patrol boat, which headed for the port of Dunkirk.
Search and rescue operations remain under way in the Dover Strait, with a French Navy helicopter continuing to scour the area.
Lisa Doyle, director of advocacy and engagement at the Refugee Council, said: “This tragic loss of life is a sobering reminder that the odds are stacked against ordinary men, women and children, who are desperately struggling for safety and protection.
“Every day, people are forced to flee their home through no fault of their own. We can do more to make the journey safer.”
She urged the Government to “change course” and create and commit to safe routes to asylum.
Following days of bad weather in the Dover Strait, lighter conditions on Thursday have seen a flurry of crossing attempts.
The latest bids to reach the UK come after French authorities intercepted at least 108 people trying to cross the Channel on Wednesday, with one person having to be airlifted to hospital in Dunkirk.
The dangerous sea journey from France – made by more than 10,000 people including children so far in 2021 – has claimed many lives in the past.
Among them were Rasoul Iran-Nejad and his wife Shiva Mohammad Panahi, who died along with their three children when their boat capsized on October 27 2020.
Their 15-month-old son Artin was reported missing following the tragedy and it was not until June this year that police confirmed a body found on the Norwegian coast was that of the young boy.
Data compiled by the PA news agency shows the tally for successful crossings this year now stands at more than 10,700 people, despite the dangers involved in the journey.
Crossings in 2021 eclipsed last year’s annual total of 8,417 in July, PA data shows.