At least four migrants died in the English Channel on Friday morning after their boat capsized, French authorities have said.
Home Secretary Yvette Cooper described the deaths as “truly awful”.
More than 60 people were reported to be on the vessel when it got into trouble off the coast of northern France at about 4.30am.
A navy patrol boat was alerted overnight that people had fallen into the sea near Boulogne-sur-Mer.
Some 63 people were rescued but four found "unconscious" could not be saved.
A helicopter and a fishing boat also helped in the rescue effort, the coastguard added.
Ms Cooper said: "The further loss of life in the Channel this morning is truly awful. My thoughts are with all those affected.
"Criminal gangs are making vast profit from putting lives at risk.
"We are accelerating action with international partners to pursue and bring down dangerous smuggler gangs."
Latest Home Office figures show 419 people, including children, made the journey across the Channel in six boats on Tuesday.
More than 14,000 migrants have made the perilous trip from France to the UK this year alone.
At the Nato summit in Washington this week, Sir Keir Starmer acknowledged that the number of people trying to cross the Channel may get worse before it gets better.
He declined to pledge to “stop the boats” or put targets on reducing crossings.
”Nobody but nobody should be making these crossings,” Sir Keir said.
“The numbers are going up, not down. That is why we want to smash the gangs to stop those crossings. What I’m not going to do is pick an arbitrary date, an arbitrary number because that hasn’t worked in the past.”
The latest incident comes after a four-year-old girl and four other people drowned while trying to cross the Channel on April 23.
The child, a woman in her early 30s and three men died after setting off from Wimereux beach in northern France.
Ms Cooper has vowed to appoint a leader of the a new Border Security Command within weeks.
The project is Labour's alternative to the previous Tory government's Rwanda policy, which Sir Keir scrapped when he became Prime Minister last week.
Instead, he promised to divert £75million from the scheme to deport some people to the African nation and set up the Command unit, which will draw together the work of intelligence agencies, police, Immigration Enforcement and Border Force.
The government hopes it will reduce small boat crossings and help break down the people smuggling gangs who traffic people across the water.
However Kevin Saunders, a former chief immigration officer for Border Force, has expressed concern about the government scrapping the Rwanda plan.
News of the scheme had caused "unease in the camps in northern France", he told Times Radio.
"They were very, very worried. And we saw people fleeing to the Republic of Ireland because they didn't want to be included in it," he said.
