A 53-year-old man was arrested in the parish of Ajuda on suspicion of possessing a prohibited weapon, the Lisbon PSP said on Tuesday.
PSP said in a statement that agents were called to a business establishment where there was information of disrespect between several individuals. Arriving at the scene, they encountered a man who had a knife.
Given the events and witness testimony that the suspect was involved in the riot, authorities detained the man to prevent him from using the knife on anyone.
The Ministry of State Service, the local criminal authority of Lisbon and the petty crimes department notified the detainee of the need for enforcement measures.