Foreign Secretary Lord Cameron said the “heartbreaking” deaths of four migrants as they tried to cross the English Channel showed “we’ve got to stop the boats”.
Ministers have been informed that the people died in an attempt to launch from French waters, the PA news agency understands.
The incident happened near Wimereux at around 2am on Sunday, triggering a major emergency response as 72 people, including 10 children, were rescued and taken to Calais while one person was rushed to hospital, French paper La Voix du Nord said.
Speaking on the BBC’s Sunday With Laura Kuenssberg, Lord Cameron said: “It’s heartbreaking when these things happen, and the loss of life that takes place.
“And you can only think about what an appalling end it would be, and the cold waters of the Channel in the middle of the night. It breaks my heart to hear about it.
“But it just shows we’ve got to stop the boats, we’ve got to stop this illegal trade in human beings.”
The former prime minister argued that the solution is forcibly removing unauthorised arrivals to Rwanda, with Rishi Sunak’s Bill to get the stalled policy up and running returning to the Commons for crunch votes this week.
Labour leader Sir Keir Starmer described the incident as a “tragic loss of life” but disputed the solution.
“I don’t know the details, in a sense we don’t need to know the details. To lose your life in a small dinghy or boat in the winter sea in the Channel is just awful,” he told the BBC.
But on the Rwanda plan advocated by Lord Cameron, he said: “I think he is wrong about that.
“I absolutely agree that we need to stop these Channel crossings.
“They are dangerous, we have lost control of our borders, and we need to do something to stop the boats.
“Now I think the starting place for that is to go after the criminal gangs that are running this vile trade.”
French media said the migrants got into difficulty while trying to board the boat in darkness and cold temperatures.
A Navy helicopter, police and 50 firefighters were involved in the rescue operation.
The Refugee Council called for “decisive action” to stop Channel crossings following the “terrible loss of life”.
Chief executive Enver Solomon said: “The sad reality is that this is not the first time we are waking up to such devastating news.
“With no meaningful commitment from the Government to expand safe routes for refugees, it’s only a matter of time before tragedy strikes again.
“This must act as a wake-up call to take decisive action and reduce dangerous Channel crossings by providing safe routes for those fleeing war-torn countries or repressive regimes.
“Rather than pushing ahead with unlawful and costly policies such as the Rwanda plan, the Government must put in place safe routes and seek to treat refugees and people seeking asylum with compassion and fairness in line with our country’s values.”
Sonya Sceats, chief executive of charity Freedom from Torture, described the proposed Rwanda Bill as “cruel”.
She said: “This distressing news comes days before the cruel Rwanda Bill is back in Parliament. Time and time again, it’s survivors and refugees who are paying the price for this Government’s inhumane and punitive policies.
“We urgently need an asylum system that’s welcoming, fair and compassionate at its heart.”
The Home Office has been approached for comment.
The UK Coastguard could not comment because the incident took place in French territorial waters.
Meanwhile, the leaders of three groups on the Tory right warned the Prime Minister they could vote against his Rwanda Bill if he does not bow to their demands to toughen the legislation.
Mark Francois, Sir John Hayes and Danny Kruger urged colleagues to join them in “standing firm” when the “simply not good enough” legislation faces key votes this week.
The Bill, which the Prime Minister has placed as central to his promise to “stop the boats”, will reopen a rift in the Conservatives when it returns to the Commons on Tuesday.