20 are in custody while 50 have been declared absconders
A case has been lodged against PPP workers and Senator Mustafa Nawaz Khokhar for attacking police personnel and causing a disturbance in Islamabad.
The case was lodged at the Secretariat police station a day after PPP workers gathered when PPP leaders Bilawal Bhutto Zardari and Asif Ali Zardari appeared before NAB at the bureau's Islamabad office on March 20.
They clashed with the police and attempted to enter NAB's building.
Twenty workers are in custody and 50 others have been declared absconders.
They have been charged under sections 109 (abetment), 341 (wrongful restraint), 188 (disobedience to public order), 149 (collective punishment for an unlawful assembly), 147 (rioting), 353 (assault on a public official to deter him from his duty) and 186 (obstructing a public servant from discharging their duties) of the Pakistan Penal Code.
They gathered at the NADRA Chowk and pushed their way to the NAB office gate. Nine police officers and a Geo TV journalist were injured in the clash.