"No one has reported any symptoms of illness so far," Fintor said, adding that they were under observation. "We're taking normal routine precautions."
The envelopes were sent to the U.S. Consulate in Karachi on Thursday and the U.S. Embassy in Islamabad on Friday. Fintor said both facilities have remained open and are operating normally, with no plans to close them.
"Embassy personnel followed established response procedures," he said. "We applaud the rapid and appropriate response by our mailroom and security staff to contain any potential threats. We take threats of this type very seriously, hoax or not."
Rob McInturff, a State Department spokesman in Washington, also praised staffers for their quick reaction.
Fintor would not say where the envelopes had been mailed from, pending an investigation, or to whom they were addressed.
