Sindh police on Monday registered a case against scores of Pashtoon Tahaffuz Movement (PTM) leaders and workers under terrorism charges after the party held a rally in Karachi's Sohrab Goth area on Sunday.

According to the FIR of the incident, police accused speakers at the rally of using "undesirable language against state institutions". The FIR (22/2019) was registered on behalf of the State through Sohrab Goth Station House Officer Rao Zakir.

Editorial: Rally in Karachi

According to the contents of the FIR, the workers of PTM, "under directions of Manzoor Pashteen organized the rally at a ground behind Al-Asif Square on Sunday."

"The complainant SHO, who was patrolling the area, after receiving information rushed to the spot and asked the PTM president of the area, Naurazay Tareen, to furnish permission of the meeting.

“He [the organiser of the rally] became jittery, created hindrance in official work and chanted slogans against state institutions and police, while other people also joined him on the stage in raising slogans,” as per the contents of the FIR.

The police alleged that the organisers did not listen to the SHO and spread provocation, "creating an atmosphere of serious fear and chaos.”

The police invoked Sections 147, 149, 186, 153-A, 500 and 505 of the Pakistan Penal Code and 7-ATA (Anti-Terrorism Act) against 250-300 persons, including 16 identified by name.

Earlier, North Waziristan MNA Mohsin Dawar had taken to Twitter to highlight the arrest and subsequent disappearance of Alamzeb Mehsud, described as an active member of the PTM and a campaigner for missing persons.

The lawmaker said that the young man's arrest was the latest in a series of incidents involving Sindh police and security agencies harassing PTM workers and activists following the party’s successful rally in Karachi on Sunday.

Dawar demanded the immediate release of Alamzaib and other PTM workers in his statement.

A senior official who wished not to be named said that Alamzeb Mehsud was arrested for being an organiser of the said rally.

Videos of what seemed to be mobile phone recordings of the arrest, which were circulated on social media, showed law enforcement officials in uniform and plain clothes brandishing weapons and forcing an unconfirmed number of young men out of their vehicle.

In one of the videos, a plainclothesman can be seen pointing a handgun directly at the car's occupants.

The regional chapter of Amnesty International also expressed concern over the disappearance of the PTM activist.

“We are concerned about reports of the disappearance of PTM activist Alamzeb Mehsud. His whereabouts must be disclosed immediately. Either produce him in court or release him without delay,” read a statement issued by the human rights watchdog.

According to the details of the incident shared by Amnesty International, “Mehsud was picked up from Karachi earlier today. Other PTM activists with him were allegedly beaten up. Freedom of peaceful assembly must be protected. Activists must never be attacked.”