French and Dutch police arrested 23 people on suspicion of smuggling 10,000 Kurdish migrants to Britain in refrigerated lorries and rubber boats, Europe's judicial agency said on Wednesday.
Nineteen suspects were held in France and four in the Netherlands after a 16-month probe, Eurojust said.
It said the gang charged up to €7,000 (Dh28,524) a person to cross the channel, and made about €70 million in profit.
"The network picked migrants up from rest areas between Le Mans and Poitiers," in western France, before taking them across the English Channel, Eurojust said.
The probe extended to the Netherlands after vehicles with Dutch licence plates were involved.
The payments were made through a "hawala" banking operation in the Netherlands, which is an informal network of money transfers conducted through face-to-face guarantees.
French authorities on Tuesday intercepted more than 40 migrants, including 11 children trying to cross the Channel to Britain.
The latest intercepts, combined with dozens of others earlier in January, are part of a continued sharp increase in dangerous crossing attempts to the UK.
Since the end of 2018, attempts by migrants from Africa, the Middle East and South Asia to make the dangerous Channel crossing have multiplied.
Rights groups have linked the sharp increase to a police crackdown on establishing migrant camps near Calais, home to a busy ferry port and the Eurotunnel, and other areas along the French coast.
Last year, 2,758 migrants were intercepted, four times the number detained the previous year, French maritime police said.
Four are known to have died trying to cross the Channel.