"We're being tortured! We're being tortured!, " the men yelled out of the small, barred window of their police van as they left a hearing before an anti-terrorism court Monday.
Officials in Pakistan deny their claims of mistreatment.
Pakistani police officials said they have emails from the group that show they contacted the Taliban and had planned to carry out terror attacks in Pakistan.
The men, aged 19 to 25, have denied the charges. They were arrested in early December in the eastern Pakistani city of Sargodha in a case that has spurred fears that Westerners are traveling to Pakistan to join militant groups.
Pakistani police have said they plan to seek life sentences for the men under the country's anti-terrorism law. The U.S. Embassy has declined to comment on the potential charges the men face in Pakistan.