PARIS — More than a dozen humanitarian and nongovernmental organizations accused local authorities of brutality against migrants as the demolition of a shantytown on the edge of Calais known as “the Jungle” continued into a third day.

Authorities moved ahead with dismantling the camp in northern France that is often used as a staging ground to cross the English channel to Britain after police scuffled with migrants protesting the demolition Monday and Tuesday.

In a statement Wednesday, the French and British humanitarian organizations – including Auberge des Migrants, Le Réveil Voyageur and Help Refugees – decried what they called the “mass gassing” of migrants by local authorities.

The French government had promised the dismantling of the camp would be a “humanitarian operation.” But bulldozers and police arrived first thing Monday morning, and riots broke out among migrants. As a ground crew destroyed homes, migrants responded with rocks and police with tear gas.

The groups said that the government’s “soothing rhetoric” was “only intended to disguise the reality” – a direct response to remarks last week from Interior Minister Bernard Cazeneuve promising a methodical demolition.

That reality, they alleged, included rubber bullets used against migrants assembled in peaceful protest, and several club beatings Monday and Tuesday. Many refugees, the 16 co-signers said, were “ordered to leave their homes in a time frame between 1 hour and 10 minutes,” in many cases without time to gather their belongings, including crucial identity documents.

The French decision to raze the makeshift settlement in Calais reflects wider measures across Europe to tighten border controls and curb movements amid a historic wave of migrants fleeing war and poverty in North Africa and the Middle East.