A passenger told Pakistan's GEO TV that the two men arrested on board a Pakistan International Airlines plane had tried to move towards the cockpit during the flight.
Nauman Rizvi told the news channel that after the men were taken away by police, the flight crew told passengers there had been a terrorist threat and that the pilot had raised an alarm.
Another passenger, Umari Nauman, told Sky News, "The cabin crew informed us that basically they tried to come into the cockpit a few times, and because they had been asked not to do that they got into a bit of an argument with the crew and made a few threats".
Ms Nauman said all the passengers had been ordered to leave their possessions on board before leaving the plane.
She also said helicopters escorted the aircraft before landing.