Police are trying to determine whether five Americans detained in Pakistan had planned to attack a complex that houses nuclear power facilities.
The young Muslim men, who are from the Washington, D.C., area, were picked up in Pakistan earlier this month in a case that has spurred fears that Westerners are traveling to the South Asian country to join militant groups.
Pakistani police and government officials have made a series of escalating and, at times, seemingly contradictory allegations about the men's intentions, while US officials have been far more cautious, though they, too, are looking at charging the men.
A Pakistani government official alleged Saturday that the men had established contact with Taliban commanders and planned to attack sites in Pakistan. Earlier, however, local police accused the men of intending to fight in Afghanistan after meeting militant leaders.