The Anti-Terrorism Court in Karachi has indicted 26 workers of Muttahida Qaumi Movement (MQM) in more than 50 cases.
The MQM activists were accused of possessing explosives and illegal weapons.
They were arrested by Rangers during a raid at MQM headquarters Nine-Zero in March, last year. They include Faisal Alia Mota, Amir Alia Sarphata, Ubaid K-2 and others.
The accused have pleaded not guilty.
The court has summoned investigation officers and witnesses on next hearing.