Activists accused officers of using 'pure violence', including striking people on the head. Police also said they were attacked.
German police said on Sunday they had almost finished removing climate activists from a German village that will be destroyed to make way for a coal mine expansion.
Both sides accused each other of violence.
In an operation that began on Wednesday, hundreds of officers and riot police cleared around 300 activists from the western German hamlet of Lützerath.
The clear-out was initially supposed to last for weeks, but the police said on Sunday that only two of them remained in the village, holed up in an underground structure.
"There are no more activists in the Lützerath region," they said.
The site, which has become a symbol of resistance to fossil fuels, attracted thousands of protesters on Saturday, including Swedish climate activist Greta Thunberg.
The organisers of the movement claimed that 35,000 people had gathered there, while the police estimated their number at 15,000.
Protests focused on the extension of an open pit mine, which will lead to the disappearance of Lützerath, in the Rhine basin, between Düsseldorf and Cologne.
Several demonstrators accused police on Sunday of "violently" repressing their rally the day before, which degenerated into clashes that injured dozens of police and demonstrators.
A spokeswoman for Indigo Drau, who organised the demo, accused the police of “pure violence” during a press conference. She said officers had beaten activists “without restraint”, including hitting them in the head.
Dozens of injuries, some serious, were reported among the ranks of the protesters. Twenty were hospitalised, according to a nurse from the activist group, Birte Schramm.
Police said on Sunday that around 70 of their officers had been injured the day before.
"We were targeted by projectiles, with stones, mud, fireworks," spokesman Andreas Müller told AFP.
Several police vehicles were damaged, particularly by stone throwing, and a large number of police vehicle tires were punctured, police said.
Investigations have been opened into about 150 cases for resisting police officers, property damage or breach of public order.
Twelve people in total were arrested or taken into custody.
Many activists had hidden inside tree houses and on the roofs of buildings in order to complicate evacuation operations.
The situation on the ground had become "very calm" again on Sunday, according to the police.
The evacuation operation in Lützerath was politically delicate for the coalition of Social Democrat Olaf Scholz, which governs with environmentalists, accused by activists of having betrayed their commitments.
Germany's government considers the extension of the mine managed by the giant RWE necessary for energy security, which must compensate for the interruption of Russian gas deliveries.