Some 2,500 officers raided the decade-old camp at Notre-Dame-des-Landes on Monday, destroying makeshift buildings topped with corrugated iron, a giant tent, a watchtower, and a sheep shed and cheese-making area, AFP reported.
The assault in a wooded area near the city of Nantes has seen dozens of rounds of tear gas fired, as well as stun grenades, while the occupants and demonstrators have responded by throwing petrol bombs and rocks at the security forces.
The activists have used tractors and burning barricades of tyres, wooden pallets, hay bales and electricity poles in an effort to keep the police at bay.
Two policemen suffered minor injuries on Tuesday, a security source told AFP, while around six demonstrators were hurt.
Activists opposed to the building of an airport began squatting on the farmland in 2008 and have since built up a community they bill as a model of sustainable farming and political debate.
In January, the government scrapped plans for the airport and told the protesters to clear out by spring.
The government has said the main aim of the operation is to retake control of a key road that runs through the area that has been blocked for five years.