Furious at the violation of its COVID-19 protocols at a hotel in Rawalpindi, the PCB said any player or official breaking the bio-bubble in future will face immediate expulsion from the tournament.
The PCB didn't name the players but according to media reports, the violators include Fakhar Zaman, Imam-ul-Haq, Khurrum Manzoor, Muhammad Hafeez, Rashid Khan, Basit Ali, Kamran Akmal, Sohail Khan, Abdul Razzaq, Anwar Ali, Yasir Shah and Usman Shinwari.
PCB's director of high performance centre, Nadeem Khan, called it "completely unacceptable".
"The PCB is disturbed and disappointed that some senior players and officials have breached the bio-secure bubble during the National T20 Cup. In doing so, they have put at risk the integrity of the tournament and health and safety of their colleagues."
"This is completely unacceptable to the PCB and following meetings with the concerned players and their team officials, it has been agreed there will be zero-tolerance for future breaches and those violating the protocols will be expelled from the ongoing and future tournaments."
He said the players and officials must show responsibility as the world is watching and international cricket is "standing at our doorsteps".
Their irresponsible actions can jeopardise all the efforts of the PCB in organising events and inviting teams during these challenging times.
COVID tests were performed on the nine players but their reports returned negative.
The 12 individuals took care of the expenses incurred in conducting the tests, besides receiving warnings.