At least 10 migrants have died after the vessel they were in capsized on its way across the Channel from France to Britain, La Voix du Nord newspaper reports, with a major operation under way to rescue more than 50 people.
A French coast guard spokesperson earlier on Tuesday said 10 people were in a critical condition.
The British coast guard did not immediately respond to a request for comment.
In a sign of the severity of the situation, CNews television said outgoing French Interior Minister Gerald Darmanin was expected on site, near the town of Boulogne-sur-Mer, later in the afternoon.
Tackling illegal immigration has been a priority for both the British and French governments.
More than 2000 people have arrived in Britain on small boats over the past seven days, according to UK government figures.
Last week, French President Emmanuel Macron and British Prime Minister Keir Starmer pledged to work closer together to dismantle migrant smuggling routes.
The Channel is one of the world's busiest shipping lanes and its currents are strong, making the crossing on small boats dangerous.
In August, two people were found dead after a boat carrying migrants trying to cross the Channel ran into difficulties.
