At least 31 migrants were killed after their boat drowned in the English Channel on their way to Britain, in what France's interior minister described as the "worst catastrophe involving migrants on the treacherous trip to date."

The boat was suspected to be carrying 34 individuals, according to Interior Minister Gerald Darmanin. Authorities discovered 31 bodies on Wednesday, including five women and a young girl, as well as two survivors, he said. One individual looked to be still missing. The nationalities of the travelers were unknown at the time.

Increasing numbers of people fleeing conflict or poverty are undertaking the risky journey from France in small, unseaworthy ships in the hopes of obtaining asylum or better chances in the United Kingdom.

Late Wednesday, a joint French-British search for survivors was still underway.

Darmanin told reporters in the French port city of Calais that four suspected traffickers were arrested on suspicion of being linked to the sunken boat on Wednesday. Two of the suspects, he added, later appeared in court.