About 2,000 migrants living under a flyover in Paris were cleared from their makeshift camp by police.
Officers launched a raid on Tuesday to tear down the campsite, sparking panic among its residents.
Asylum seekers, including women and children, were led on to 70 buses to be ferried to accommodation centres. But when a crush to board the vehicles ensued, police fired tear gas into the crowd.
One French human rights group said the operation was part of an "endless and destructive cycle" that did nothing to help the people in need.
The camp, a mass of tents and improvised shelters made of plastic sheeting and cardboard boxes, was built under the A1 motorway, close to the national sports stadium, the Stade de France.
Philippe Caro, a volunteer with Solidarite Migrants Wilson, a group that helps people at the camp, said the alternative accommodation being offered was largely inadequate.
"In spite of everything, there are going to be people left out on the street," he said. The people at the camp were predominantly asylum seekers from conflict zones, including Afghanistan, Somalia, and Sudan.
Representatives of non-government organisations that work with the migrants said there were at least 2,000 people at the site.
Several hours after the raid started, hundreds were still waiting to board buses.
"These camps are not acceptable," said Paris police prefect Didier Lallement. "This operation aims to ensure that people with the right to be here are given shelter and those who do not have that right do not remain on French territory."
Police said their objective was the health and safety of the people at the camp, especially in light of the coronavirus pandemic, and insisted those moved on from the site would be offered alternative accommodation.
France has joined other European countries, among them Italy, Britain and Sweden, in taking a tougher approach on migration since the outbreak of the Syria conflict in 2011 triggered a migrant crisis across Europe.
Some French opinion polls show that voters are worried about the issue, driving support for far-right leader Marine Le Pen, likely to be Emmanuel Macron's main opponent in the next presidential election in 2022.
France is in the middle of a second national lockdown to tackle rising cases of coronavirus, and has about 33,500 people in hospital with Covid-19, of whom nearly 5,000 are receiving intensive care.
