At least 29 migrants have drowned trying to cross the Channel, the MP for Calais has told Sky News.
Pierre Henri Dumont said 29 was the most up to date he had – earlier the town’s mayor put it at 27.
Others are thought to be injured after their inflatable dinghy capsized near Calais this afternoon.
One UK patrol boat, one French lifeboat, and three helicopters are involved in rescue efforts as five people remain missing, said French maritime minister Annick Girardin.
Prime Minister Boris Johnson is holding a meeting of the UK’s emergency COBRA committee in response.
He said he was “shocked, appalled and deeply saddened” by the deaths.
It is the worst-ever incident involving migrants in the Channel, according to French maritime authorities.
Franck Dhersin, deputy head of regional transport, said many bodies were probably still at sea and the death toll was likely to rise.
France’s interior minister, Gerald Darmanin, is heading to the area and prime minister Jean Castex called it a “tragedy”.
Fisherman Nicolas Margolle said he had seen two small dinghies, one with people onboard and another empty.
He said another fisherman had called rescuers after seeing the empty dinghy and 15 people motionless in the water.
A French naval boat retrieved an unidentified number of dead and injured, including some who were unconscious, a maritime authority spokesperson said.
Conditions on the Channel were described as cool but calm, which may explain why there were a number of crossings on Wednesday.
Other migrants were brought ashore at Dover and Dungeness.
The Dover Strait is the world’s busiest shipping lane and more than 25,700 people have made the dangerous journey to the UK this year.
That figure is three times the total for 2020, according to data compiled by the PA news agency.
Dover MP Natalie Elphicke said: “This is an absolute tragedy. It underlines why saving lives at sea starts by stopping the boats entering the water in the first place.
“As winter is approaching the seas will get rougher, the water colder, the risk of even more lives tragically being lost greater.
“That’s why stopping these dangerous crossings is the humanitarian and right thing to do.”