A second official, who declined to be identified, said the evacuation would take several days.
"It's about 1,500 minors who will go to reception centers, where they will meet personnel from the Home Office (British interior ministry)," the official said.
Hollande said on Monday that minors who do not leave for Britain will be taken care of by the French state, adding that in a few days there would be no more foreign minors in Calais.
The Calais camp came to symbolize Europe's fraught efforts to cope with a record influx of migrants fleeing strife in countries from Afghanistan to Sudan.
Ahead of the transfer, local police said about 100 Eritrean and Afghan minors had fought in the southern part of the camp on Tuesday evening, forcing riot police to intervene.