A man identified as Rami Mackenzie, 27, was arrested near North Waziristan. Pakistani authorities believe he was an expert in the manufacturing of suicide vests, Pakistan's Dawn newspaper reports.
Mackenzie was wearing the traditional burqa. Female security officials found a fake Pakistani passport on him when he was searched at a routine checkpoint.
Authorities say he crossed the border from Afghanistan a few months ago. Western officials have raised concerns lately over their citizens traveling to the region to take part in or train for terrorism operations.
Faisal Shahzad, a 30-year-old naturalized U.S. citizen born in Pakistan, pleaded guilty Monday in a federal court in New York to trying to set off a bomb in New York's Time Square.
Shahzad said he had traveled to Pakistan to receive training in explosives.
U.S. authorities also charged American citizen David Coleman Headley with conducting "extensive surveillance" for Pakistani terrorist group Laskhar-e-Toiba in the 2008 attacks on Mumbai.