FBI agents and U.S. Embassy officials were questioning the five, ages 18 to 24 and all from Washington, D.C., suburbs, in the central Pakistani town of Sargodha.

The five had an Internet-powered interest in jihad, or holy war, and had e-mail contact with a mysterious Pakistani militant, the police said. The men's planning appeared amateurish, however. Although police in Sargodha played up the Americans' alleged links to al-Qaeda and suggested they were involved in a major terrorist plot, the absence of radical connections may have thwarted their purported ambitions.

Police said that after searching in vain for a radical group that would accept them, the five ended up in Sargodha, where Umar Farooq, Khalid Farooq's son, has family links. According to the police, their Pakistani e-mail contact told them to proceed to North Waziristan, part of Pakistan's Taliban-controlled tribal area bordering Afghanistan.

The case has fueled fears about American Muslims, especially those of Pakistani origin, being drawn to militancy in Pakistan.