A total of 27 people were arrested during the Sudoeste Festival, a five-day event in Zambujeira do Mar in the Alentejo, from August 4 to 8.
GNR police arrested 20 people for drug trafficking, five for driving under the influence of alcohol, one for driving illegally and another for the possession of an illegal weapon.
The GNR also seized 3,102 doses of hashish, 335 of cannabis, 95 of cocaine, 295 of ecstasy, LSD and opium and 20 cannabis plants.
