The discovery of a "suspicious" white powder saw Fortitude Valley’s police station evacuated on Sunday night.
The fire brigade, police explosives unit and illicit laboratory investigation team were called to the Brookes Street station about 5pm yesterday.
The site was later declared safe and the powder was identified as a corrosive agent.
A police spokesman said officers seized a car in Bowen Hills about 2am on Sunday, which was later taken to the police holding yards in Geebung.
Contents from the car, initially believed to be drug-making equipment, were then transported to the Fortitude Valley station.
However police later found a suspicious package in the car that was of an “explosives nature”, the spokesman said.
The discovery prompted the evacuation of the Fortitude Valley station as a precaution.
A 42-year-old man and 29-year-old woman, both from Ipswich, were arrested when the car was seized.
The pair were released pending further investigations.