President Emmanuel Macron appealed Thursday to neighboring European countries to do more to stop illegal migration into France after at least 27 people died trying to cross the English Channel.

Macron said that when migrants arrive on French shores with hopes of heading to Britain “it is already too late.”

Speaking a day after the deadliest migration tragedy to date on the dangerous sea lane that separates France and Britain, Macron said France is deploying army drones as part of stepped-up efforts to patrol the northern French coastline and help rescue migrants at sea.

But he also said that France is a “transit country" for migrants aiming for Britain and that a greater collective effort is needed.

“We need to strengthen cooperation with Belgium, the Netherlands, Germany, but also the British and the (European) Commission,” he said on a visit to Croatia. “We need stronger European cooperation.”

The French leader described the dead in Wednesday's sinking as "victims of the worst system, that of smugglers and human traffickers.”

France has never had so many officers mobilized against illegal migration and its commitment is “total,” he said. But he also made clear that it wants more help.

"When these women and men arrive on the shores of the English Channel it is already too late,” he said.

The French prosecutors’ office tasked with investigating the sinking said the dead included 17 men, seven women and two boys and one girl thought to be teenagers. Magistrates were investigating potential charges of homicide, unintentional wounding, assisting illegal migration and criminal conspiracy, the prosecutors’ office said.

Interior Minister Gerald Darmanin said children and pregnant women were among the dead.

He announced the arrest of a fifth suspected smuggler thought to have been involved. He said authorities are working to determine the victims' nationalities. Two survivors were treated for hypothermia. One is Iraqi, the other Somali, Darmanin said.

In their immediate response to the sinking, French authorities initially gave slightly differing figures on the numbers of dead, from at least 27 to 31. The figure that Darmanin used Thursday morning on RTL radio was 27.

Darmanin on Wednesday had already announced the arrest of four suspected smugglers on suspicion of being linked to the sunken boat. He told RTL that a fifth suspected smuggler was picked up overnight.

The fifth suspect was driving a vehicle registered in Germany, Darmanin said. He said criminal groups in Belgium, the Netherlands, Germany and Britain are behind people-smuggling networks.

He also called on those countries to cooperate better in the battle against smugglers, saying they don't always respond fully to French judicial requests for information.

“Britain and France must work together. We must no longer be, in effect, the only ones able to fight the smugglers," the minister said.

“The smugglers buy boats, Zodiacs, in Germany with cash," he added. "The smuggler arrested overnight has German plates; he bought his Zodiacs in Germany.”

The minister also took a swipe at British government migration policies, saying France expels more people living in the country without legal permission than the U.K. Illegal migration from France's northern shores to Britain has long been a source of tension between the two countries, with both sides blaming each other even as their police forces work together to try to stop unseaworthy boats from crossing the English Channel. The issue is often used by politicians on both sides pushing an anti-migration agenda.

“Clearly, immigration is badly managed in Britain," Darmanin said.

He also suggested that by hiring people living in the country illegally, British employers are encouraging illegal migration to English shores.

“English employers use this labor to make the things that the English manufacture and consume," he said. “We say reform your labor market. Tell English employers that we need them to be as patriotic as the conservative government.”

Ever-increasing numbers of people fleeing conflict or poverty in Afghanistan, Sudan, Iraq, Eritrea or elsewhere are risking the perilous journey in small, unseaworthy craft from France, hoping to win asylum or find better opportunities in Britain. The crossings have tripled this year compared to 2020.

British Prime Minister Boris Johnson and Macron spoke after Wednesday’s tragedy and agreed “that it is vital to keep all options on the table to stop these lethal crossings and break the business model of the criminal gangs behind them,” Johnson’s office said.

Macron advocated an immediate funding boost for the European Union’s border agency, Frontex, and an emergency meeting of European government ministers, according to his office.

“France will not allow the Channel to become a cemetery,” Macron said.