Out of the 10 players and one official, who had earlier tested positive during the PCB testing programme, Fakhar Zaman, Mohammad Hasnain, Mohammad Hafeez, Mohammad Rizwan, Shadab Khan and Wahab Riaz tested negative in their second tests.
Players who have again tested positive were Haider Ali, Haris Rauf, Kashif Bhatti and Imran Khan, along with masseur Malang Ali.
PCB said all who have tested positive did not report any symptoms prior to testing.
The six players will undergo a third round of testing at some stage next week.
Despite the developments, PCB CEO Wasim Khan said the tour is on track.