A pregnant woman is among 12 people who have died after a boat carrying dozens of migrants capsized in the English Channel, a local mayor has told the BBC.

The mostly female dead include several children, Interior Minister Gérald Darmanin said, adding that two more people are missing.

The French coast guard said more than 50 people had been rescued off the Gris-Nez cape, near the town of Boulogne-sur-Mer. Two were said to be in critical condition.

Mr Darmanin said that the boat was overloaded, and fewer than eight people had life jackets on.

The disaster is the deadliest loss of life in the Channel this year.

The mayor of Boulogne-sur-Mer, Frédéric Cuvillier, told the BBC that a pregnant woman had died.

The city’s prosecutor, Guirec Le Bras, said that those killed were “primarily of Eritrean origin,” but that officials “do not have consolidated details that would allow us to specify the exact nationalities”.

Before Tuesday’s incident, 30 people had already died crossing the Channel in 2024 – the highest figure for any year since 2021, when 45 deaths were recorded, according to the UN’s International Organisation for Migration.

Mr Darmanin said French authorities are preventing 60% of small boat departures. But people smugglers are cramming up to 70 people on the same vessels which used to carry 30 to 40 people – leading to deadlier shipwrecks.

He urged the UK and EU to agree a “treaty on migration” to curb small boat crossings.

UK Home Secretary Yvette Cooper described the incident as “horrifying and deeply tragic”.

“The gangs behind this appalling and callous trade in human lives have been cramming more and more people onto increasingly unseaworthy dinghies, and sending them out into the Channel even in very poor weather,” she said.

The effort to “dismantle these dangerous and criminal smuggler gangs and to strengthen border security is so vital and must proceed apace,” she added.

Steve Smith, CEO of Care4Calais, a charity set up to aid migrants in Calais, said: “These tragedies have occurred with much more frequency.”

“Every political leader, on both sides of our Channel, needs to be asked: ‘How many lives will be lost before they end these avoidable tragedies?'”

The French coastguard said helicopters, Navy boats and fishing ships were involved in the rescue operation.

The number of people making the dangerous crossing across the English Channel in small boats has risen, with more than 135,000 people coming to the UK by this route since 2018.

More than 21,000 people have crossed the Channel this year.

That is more than in the same period in the previous year, but fewer than in 2022. The number of people who crossed in 2022 – 45,755 – was the highest since figures were first collected in 2018.

Both Labour and the previous Conservative government have vowed to tackle the problem.

UK Prime Minister Keir Starmer cancelled the previous Tory government’s plan to send some asylum seekers to Rwanda, which was first announced in 2022 but never put into effect.

Sir Keir has vowed to take tougher measures to “smash” the people-smuggling gangs responsible.

Downing Street says it has already taken action to target the criminal gangs by recruiting more officers to the National Crime Agency and setting up the government’s Border Security Command.

But critics say the government should be doing more to offer safe routes for asylum seekers.

Amnesty International UK said on Tuesday: “No amount of ‘smash the gangs’ policing and Government rhetoric is going to stop these disasters from unfolding time and again if the needs of people exploited by those gangs remain unaddressed.”