A woman has died while attempting to cross the English Channel on board a "heavily loaded" boat that was "in difficulty", the French maritime authorities have said.
Officials said that at 04:30 BST, a French patrol boat was on site and some of the people on the overloaded vessel off the coast of Calais requested assistance.
One person was found "unconscious" and was taken to a hospital in Boulogne-sur-Mer in northern France via helicopter, where she later died.
At least 30 other people were rescued but several on the vessel refused assistance and remained on board, authorities said.
Overnight, a migrant vessel leaving the Calais coast was reported to a French operational surveillance and rescue centre.
French maritime authorities said in a statement that two patrol units were deployed to find the boat and arrived at around 04:30 BST to find it was "in difficulty".
Some people on board requested assistance and the patrol units started rescuing people "in distress" and began moving people off the boat, they added.
They said: "During the transfer, it was observed that one person on the migrant vessel was unconscious; the person was taken on board and given first aid immediately."
A helicopter airlifted the woman to a hospital in Boulogne-sur-Mer and later died.
At least 30 survivors were brought to the port of Calais and taken care of by rescue services and the border police.
The French maritime authorities said several people on board the migrant vessel refused assistance and remained on board.
"Considering the risks of people falling overboard or getting injured during a forced intervention, the decision was made to allow the remaining individuals on the vessel to continue their journey," they said.
UK Home Office figures show 342 migrants arrived in small boats on 20 July and 21 July.
More than 14,000 people have crossed the Channel so far this year.