Yet, organizations say, at least 200 more migrants, mostly young men from Eritrea, have reached Calais since that meeting, where Mr. Macron and Ms. May announced an accord that aimed to reduce the time unaccompanied minors spent there.

“They mistakenly thought that they could reach Britain more easily,” Mr. Guennoc said.

But the French government has showed no leniency. “The message I want to get across is that if you want to go to Britain, it’s not here you should come,” Mr. Collomb said on Thursday while visiting local authorities and security forces in Calais.

France received a record number of asylum claims last year — 100,000 compared with 85,000 in 2016 — but no other town has embodied the challenges posed by immigration more than Calais, where a squalid encampment known as the Jungle was once home to more than 10,000 people before it was dismantled in 2016.

“Under no circumstances will we allow the Jungle to come back,” Mr. Macron said in January, when he visited Calais to explain his policies on immigration.

The government plans to present legislation on immigration and asylum in the spring, and Mr. Macron has vowed to step up deportations against those who come to France for economic reasons and speed up the process for those who are fleeing conflicts and persecution. This approach, he argued, would mix “humanity” with “efficiency.”

Mr. Collomb, the interior minister, has become the face of the latter. In Calais, he has expressed support for the police, whose treatment of migrants was criticized by a Human Rights Watch report that denounced their systematic use of pepper spray against migrants.

When a report by the Ministry of Interior found “it plausible that there was a breach in security force doctrine and ethics,” Mr. Collomb dismissed some of the accusations.