Qurbanli, of the opposition NIDA youth movement, was arrested near his house in the town of Hirdalan on September 29.
An Interior Ministry official told RFE/RL that Qurbanli is suspected of involvement in illegal drug activities, adding that Qurbanli resisted arrest and that "illegal documents and objects" were found in his office.
The official provided no more details.
Qurbanli's colleagues say police brought him handcuffed to the office of another opposition youth group, Positive Changes, and questioned him there on September 29 about NIDA leaflets.
The official statement came after Qurbanli's relatives complained to RFE/RL that they had received no explanation about Qurbanli's arrest or whereabouts since his detention.