Five people were detained Saturday as Greek police moved to evacuate two recently cleared Athens squats reoccupied by suspected anarchists, state agency ANA said.
The anarchists threw paint and projectiles at police, who responded with tear gas, ANA said.
The new conservative government of Prime Minister Kyriakos Mitsotakis is enforcing a tough policy on squats, claiming that they are being used to spring attacks on police and smuggle drugs.
Rights groups counter that many abandoned buildings in Athens are often used to shelter homeless refugees.
In November, the minister for police gave anarchists a two-week ultimatum to abandon around 40 squats around the capital, some of them dating to the 1990s.
Saturday's operation in the district of Koukaki -- a top home-sharing area near the Acropolis -- followed a December 18 raid by police that sparked a political row after an award-winning director living next door to one of the squats claimed he and his sons were illegally arrested and beaten.
The main opposition leftist Syriza party has accused the government of authoritarian behaviour.
Police escort a detained man into a van after a raid on a "squat" in Koukaki, a central district of Athens in December 2019