More than 20 migrants have died after a boat sank off the coast of Calais on Wednesday, French police have told AFP news agency.
Fishermen initially reported discovering 15 bodies floating in the water at around 14h CET.
A French navy vessel recovered five dead bodies and five other people unconscious.
The provisional death toll was later increased to “more than 20”.
It comes as record numbers of migrants have attempted to cross from France to the United Kingdom this year.
Interior Minister Gérald Darmanin said on Twitter that he was on his way to the scene.
“Strong emotion in front of the tragedy of the numerous deaths due to the capsizing of a boat of migrants in the English Channel,” Darmanin wrote.
“The criminal nature of the smugglers who organise these crossings cannot be overstated,” he added.
The Dunkirk public prosecutor’s office told AFP that an investigation had been opened for “aiding illegal entry and residence in an organised gang” and “aggravated manslaughter”.
So far this year, at least three migrants have drowned off the coast of Calais, while four people remain missing.
The narrow strait of water can be dangerous for attempted migrant crossings, due to strong sea currents.
An estimated 22,000 people have reached the UK in small boats this year, more than double the number in 2020.
The British government has agreed to pay France €62.7 million to increase security on its northern coast, but says the situation remains “unacceptable”.
Earlier this month, a record of 1,185 people reached the UK in a single day.