Five more Supreme Court judges received “suspicious letters” on Friday, sources told Aaj News, joining the list of jurists in the apex and high courts having received such written messages.

They added the SC staff handed over the letters to the Counter Terrorism Department. It was not yet clear whether the letters contained any toxic material like the Islamabad High Court judges received earlier this week.

This comes a day after letters allegedly laced with a toxic substance were sent to Chief Justice of Pakistan Qazi Faez Isa, Justice Athar Minallah, Justice Jamal Khan Mandokhail, and Justice Aminuddin.

The letters were received at the Receipt and Issue Branch of the apex court from where they were forwarded to the staff of the judges. The letters sent by an unknown group threatened the judges of the SC for ‘rescuing evil’.

Earlier in the day, Lahore High Court’s Justice Ali Baqar Najafi received a “suspicious” letter. He became the sixth high court judge to receive it after LHC Chief Justice Malik Shahzad Ahmad Khan, senior puisne judge Justice Shujaat Ali Khan, Justice Shahid Bilal Hassan, Justice Aalia Neelum, and Justice Abid Aziz Sheikh received it.

The recent trend started with threatening letters laced with a “white powder” sent to the Islamabad High Court on Tuesday. The first information report was registered at the capital’s Counter Terrorism Department police station under Section 507 (criminal intimidation by an anonymous communication) of the Pakistan Penal Code and Section 7 (punishment for acts of terrorism) of the Anti-Terrorism Act.

The letters while giving reference to Tehreek-i-Namoos Pakistan criticised the justice system, it said, adding that a particular photo and English word “Bacillus Anthracis” were included in the letters for the threat.

Prior to the letter, six – out of the total eight – IHC judges had written a letter to the Supreme Judicial Council over the alleged interference by the executive and the intelligence agencies in the judicial affairs.

On Thursday, Prime Minister Shehbaz Sharif said that the government would launch a probe into the matter “with a sense of responsibility”.