Dozens of people rescued and 12 others admitted to hospital after boat travelling from France to Britain capsizes.

At least 12 people have died and dozens have been rescued after the boat they were travelling in capsized during an attempted crossing of the English Channel, authorities say.

Rescuers pulled a total of 65 people from the English Channel on Tuesday in a search that lasted more than four hours, according to Etienne Baggio, a spokesman for the French agency that oversees the stretch of sea where the boat ripped apart. Doctors confirmed 12 died, he said.

Another 12 people were admitted to hospital, and two were in very serious conditions, authorities said.

“Unfortunately, the bottom of the boat ripped open,” said Olivier Barbarin, mayor of Le Portel near Boulogne-sur-Mer.

Baggio described it as the deadliest migrant boat tragedy in the English Channel this year. Many of those on board didn’t have life vests, he said. It was not immediately clear how the boat ripped open or what kind of boat it was. Some attempt the crossing in rubber dinghies.

The maritime prefecture said the boat got into difficulty off Gris-Nez point between Boulogne-sur-Mer and the port of Calais farther north.

Sea temperatures off northern France were about 20 degrees Celsius (68 degrees Fahrenheit).

French Interior Minister Gerald Darmanin went to Boulogne-sur-Mer to meet those involved in handling what he described as the “terrible shipwreck”.

He said the boat was frail and small – less than 7 metres (23 feet) long – and that smugglers are packing more and more people aboard such vessels. Most of the people on the boat were believed to be from Eritrea, and most of the victims were women, he said.

Last week, the leaders of France and the United Kingdom agreed to deepen cooperation on irregular migration in the channel.

“We absolutely must – and this is a very important point – re-establish special relations with our British friends,” Darmanin said on Tuesday.

UK Home Secretary Yvette Cooper called the deaths “horrifying and deeply tragic”.

In a statement, Cooper criticised the “gangs behind this appalling and callous trade in human lives”, adding they “do not care about anything but the profits they make”.

At least 30 refugees and migrants have died or gone missing while trying to cross to the UK this year, according to the International Organization for Migration.

Some 2,109 people have tried to cross the English Channel on small boats in the past seven days, according to UK Home Office data updated on Tuesday.

The data includes people found in the channel or on arrival.