Telangana Joint Action Committee (TJAC) convenor M. Kodandaram was here on Wednesday detained ahead of its rally of unemployed youth, police said.
Kodandaram was arrested from his residence in Secunderabad and shifted to police station as a precautionary measure.
Some other leaders and activists of the TJAC were also detained.
Scores of TJAC activists on their way to Hyderabad from different parts of Telangana were also taken into custody.
Fearing violence, the police had denied permission for the rally and imposed prohibitory orders but the TJAC had vowed to go ahead, demanding Telangana Rashtra Samithi (TRS) government to fulfill its promise to provide one lakh jobs.
Opposition parties, various people's organisations and student groups have declared their support to the rally proposed to be taken out from Sundaraiah Vignana Kendram to Indra Park.
On the other hand, the TRS alleged that extremists infiltrated into the TJAC and might create disturbances.
The police have imposed ban to foil the rally.