The letters come a day after a similar incident in Islamabad, where all eight judges in the High Court had received threatening letters with a suspicious powder in the envelopes.

In the Supreme Court, four judges including Chief Justice Qazi Faez Isa were sent the suspicious letters on April 1.

The letters were also sent to Justices Athar Minallah, Jamal Mandokhail, and Aminuddin Khan.

The letters carry the danger symbol along with a suspicious powder. All letters have now been handed to the Counter Terrorism Department.

In LHC, the letters were delivered to Justice Shujaat Ali, Justice Shahid Bilal and Justice Alia Neelum.

Following the letter, security arrangements were beefed up around the LHC and a team of the Counter Terrorism Department immediately reached the building.

Meanwhile, a FIR has been filed in Islamabad regarding the letters sent to the IHC judges.

The FIR was filed by a clerk at Pakistan Post named Qadir Ahmad. The case has been filed in the CTD police station.