Officers were called to the district court house, on Stanley St, at 1.45pm yesterday after a bag of white powder was found in the toilets.
Senior Sergeant Paula Enoka, of Queenstown, said it was taken to the airport and ''gave no result - it didn't test positive for any drug or narcotic''.
The 10cm by 6cm bag contained about 8 grams of the substance.
''We're not making any assumptions but it has the same consistency as sugar.''
No arrests have been made.
Snr Sgt Enoka said there were no concerns that the powder was a biological agent or poison, such as anthrax.