The protesters were sprayed by officers at a rally late Tuesday.
Maureira was detained on 21 October during the ongoing protests in Santiago for allegedly assaulting police officers. During his detention, the Maureira says he was beaten and sexually assaulted with a police baton. He is now suing the city for violating his human rights.
On Monday, nationwide protests renewed despite the fact that Chilean President Sebastian Pinera replaced key ministers, including the interior and finance ministers. In Santiago, protesters burned down a shopping mall, prompting the evacuation of a nearby hotel.
Chile has been mired in protests since 6 October, when the authorities increased subway fares. What started as peaceful public demonstrations have turned into wider discontent with social policies and violent clashes with law enforcement agencies. At least 20 people have been killed as a result of the unrest, Pinera's office said on Tuesday.