Three police officers were wounded in Athens on Tuesday as thousands protested against police violence, Greek authorities said.
According to police, an estimated 5,000 people took part in the march in the Nea Smyrni district of the Greek capital, after a video of a police officer beating a man with a baton went viral.
Clashes erupted when a group of protesters attacked a police station with petrol bombs, while police responded with tear gas and water cannons.
Dozens of people attacked a motorcycle police officer with stones and clubs, severely injuring him, local media reported. His life is not in danger, Greek news agency ANA said.
At least two more police officers were wounded, according to a police statement.
A dozen rubbish bins were set on fire, forcing firefighters to intervene, AFP reported.
Sunday incident sparks indignation
The march to the Nea Smyrni police station followed an incident on Sunday during a police enforcement of lockdown measures in a square in the area.
Footage of the incident shows a young man on the ground shouting: "I'm in pain", while passers-by show outrage at police behaviour.
Police said officers had earlier been attacked by dozens of people who objected to them trying to issue fines to people who were not obeying restrictions.
In an interview published Tuesday in Efsyn newspaper, the 29-year old young man said he was trying to dissuade the police officers from fining families who were sitting in the square when the incident happened.
"A policeman then came towards me and took aim at me. He pushed me before the other policemen kicked me all over the body," he told the newspaper.
An investigation has been opened into Sunday's incident.
PM calls for calm
In an address to the nation, Greek Prime Minister Kiriakos Mitsotakis appealed for calm, telling young people that "blind rage leads nowhere".
Opposition party Syriza, condemned "those who, by force, chose to tarnish a peaceful demonstration of thousands of citizens."
Media and lawyers organisations say police violence has increased in recent months, especially during students or leftist groups' demonstrations.