French police fired tear gas and water cannon at migrants and protesters who gathered in defiance of a ban on Saturday outside the shanty town near Calais known as “the Jungle”, local authorities said.
About 200 migrants and some 50 protesters assembled under a bridge to protest against living conditions in the nearby camp that President Francois Hollande has vowed to close by the end of the year.
Police clashed with migrants as they pushed them back to the camp while activists threw stones at the security forces.
Another 150 protesters who left Paris on Saturday aboard four coaches were blocked by police at a toll road about 30 miles (48 km) short of the northern port.
Thousands of migrants fleeing war and poverty, from Afghanistan to Syria, have converged on Calais over the past two years.
Many attempt to sneak onto trains using the Channel Tunnel or lorries heading to Britain, where they hope to settle. The presence of the migrants has led to tension with some residents and a permanent police deployment.
(Reporting by Pascal Rossignol in Calais and Pierre Savary in Lille; writing by Michel Rose in Paris; editing by David Clarke)