French President Emmanuel Macron has said more than 25,000 people were rescued by his border police in the north of the country on Saturday, the Interior Ministry said.
Macron told a news conference on Saturday morning that the total number of migrants in the border area had risen to 20,848.
“The majority of them are from Africa and South America, but a large number of them were also from Central America, the Middle East and Asia,” Macron said.
The number of arrivals has been rising since Saturday afternoon, when the coastguard announced it had rescued two migrants.
Macron said on Saturday that he had asked the French ambassador to London to call on other countries to open their borders to migrants.
He said the authorities had not been able to take care of migrants on their own.
The migrants had been sleeping rough in the forest and had been given water and food, he said.
Macrons office said on Sunday that more than 5,000 unaccompanied migrants were registered in the country since Friday, with more than 10,000 more waiting to be processed.
The government has warned that some migrants were hiding in the woods or on rooftops, with police often failing to check whether they were in fact migrants.
Authorities have not yet given an estimate of how many migrants are still trapped in the region.
Earlier this month, more than 2,000 were rescued off the coast of France, prompting the European Union to take measures to boost border security.