French authorities have arrested and convicted a top smuggler and his accomplice who had reigned over desperate migrants trying to sneak to Britain.

The arrests cracked the centerpiece of a lucrative network run out of Britain, where the investigation continues, according to Dunkirk deputy prosecutor Amelie Le Sant.

A Dunkirk court convicted Twana Jamal, a 36-year-old Iraqi Kurd earlier this month along with Kadir Pirout, 33. In a single month, the two arranged passage for more than 80 migrants. The monthly take was estimated at 300,000 pounds ($390,000), Le Sant told The Associated Press.

Jamal received a five-year sentence while Pirout got four years, plus fines and lifelong bans from France once their terms are served.

Across northern France, police are cracking down on migrant smugglers.